// Copyright 2017 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.

package report

import (
	"bytes"
	"fmt"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"time"

	"github.com/google/syzkaller/pkg/cover/backend"
	"github.com/google/syzkaller/pkg/osutil"
	"github.com/google/syzkaller/pkg/report/crash"
	"github.com/google/syzkaller/pkg/symbolizer"
	"github.com/google/syzkaller/pkg/vcs"
	"github.com/google/syzkaller/sys/targets"
	"github.com/ianlancetaylor/demangle"
)

type linux struct {
	*config
	vmlinux               string
	symbols               map[string]map[string][]symbolizer.Symbol
	consoleOutputRe       *regexp.Regexp
	taskContext           *regexp.Regexp
	cpuContext            *regexp.Regexp
	questionableFrame     *regexp.Regexp
	guiltyFileIgnores     []*regexp.Regexp
	guiltyLineIgnore      *regexp.Regexp
	reportStartIgnores    []*regexp.Regexp
	infoMessagesWithStack [][]byte
	eoi                   []byte
	symbolizerCache       symbolizer.Cache
}

func ctorLinux(cfg *config) (reporterImpl, []string, error) {
	symbols := make(map[string]map[string][]symbolizer.Symbol)
	vmlinux := ""
	if cfg.kernelDirs.Obj != "" {
		vmlinux = filepath.Join(cfg.kernelDirs.Obj, cfg.target.KernelObject)
		var err error
		symbols[""], err = symbolizer.ReadTextSymbols(vmlinux)
		if err != nil {
			return nil, nil, err
		}
		for _, mod := range cfg.kernelModules {
			if mod.Name == "" {
				continue
			}
			ss, err := symbolizer.ReadTextSymbols(mod.Path)
			if err != nil {
				continue
			}
			symbols[mod.Name] = ss
		}
	}
	ctx := &linux{
		config:  cfg,
		vmlinux: vmlinux,
		symbols: symbols,
	}
	// nolint: lll
	ctx.consoleOutputRe = regexp.MustCompile(`^(?:\*\* [0-9]+ printk messages dropped \*\* )?(?:.* login: )?(?:\<[0-9]+\>)?\[ *[0-9]+\.[0-9]+\](\[ *(?:C|T)[0-9]+\])? `)
	ctx.taskContext = regexp.MustCompile(`\[ *T[0-9]+\]`)
	ctx.cpuContext = regexp.MustCompile(`\[ *C[0-9]+\]`)
	ctx.questionableFrame = regexp.MustCompile(`(\[\<[0-9a-f]+\>\])? \? `)
	ctx.eoi = []byte("<EOI>")
	ctx.guiltyFileIgnores = []*regexp.Regexp{
		regexp.MustCompile(`.*\.h`),
		regexp.MustCompile(`^lib/.*`),
		regexp.MustCompile(`^virt/lib/.*`),
		regexp.MustCompile(`^mm/kasan/.*`),
		regexp.MustCompile(`^mm/kmsan/.*`),
		regexp.MustCompile(`^kernel/kcov.c`),
		regexp.MustCompile(`^mm/sl.b.c`),
		regexp.MustCompile(`^mm/filemap.c`),
		regexp.MustCompile(`^mm/folio-compat.c`),
		regexp.MustCompile(`^mm/truncate.c`),
		regexp.MustCompile(`^mm/memory.c`),
		regexp.MustCompile(`^mm/percpu.*`),
		regexp.MustCompile(`^mm/vmalloc.c`),
		regexp.MustCompile(`^mm/page_alloc.c`),
		regexp.MustCompile(`^mm/mempool.c`),
		regexp.MustCompile(`^mm/util.c`),
		regexp.MustCompile(`^kernel/rcu/.*`),
		regexp.MustCompile(`^arch/.*/kernel/traps.c`),
		regexp.MustCompile(`^arch/.*/kernel/unwind.*.c`),
		regexp.MustCompile(`^arch/.*/mm/fault.c`),
		regexp.MustCompile(`^arch/.*/mm/physaddr.c`),
		regexp.MustCompile(`^arch/.*/kernel/stacktrace.c`),
		regexp.MustCompile(`^arch/.*/kernel/apic/apic.c`),
		regexp.MustCompile(`^arch/arm64/kernel/entry.*.c`),
		regexp.MustCompile(`^arch/arm64/kernel/process\.c`),
		regexp.MustCompile(`^kernel/locking/.*`),
		regexp.MustCompile(`^kernel/panic.c`),
		regexp.MustCompile(`^kernel/printk/printk.*.c`),
		regexp.MustCompile(`^kernel/softirq.c`),
		regexp.MustCompile(`^kernel/kthread.c`),
		regexp.MustCompile(`^kernel/sched/.*.c`),
		regexp.MustCompile(`^kernel/stacktrace.c`),
		regexp.MustCompile(`^kernel/time/timer.c`),
		regexp.MustCompile(`^kernel/workqueue.c`),
		regexp.MustCompile(`^net/core/dev.c`),
		regexp.MustCompile(`^net/core/sock.c`),
		regexp.MustCompile(`^net/core/skbuff.c`),
		regexp.MustCompile(`^fs/proc/generic.c`),
		regexp.MustCompile(`^trusty/`),                // Trusty sources are not in linux kernel tree.
		regexp.MustCompile(`^drivers/usb/core/urb.c`), // WARNING in urb.c usually means a bug in a driver
		// Crashes in these files are almost always caused by the calling code.
		regexp.MustCompile(`^arch/.*/lib/crc.*`),
	}
	ctx.guiltyLineIgnore = regexp.MustCompile(`(hardirqs|softirqs)\s+last\s+(enabled|disabled)|^Register r\d+ information`)
	// These pattern do _not_ start a new report, i.e. can be in a middle of another report.
	ctx.reportStartIgnores = []*regexp.Regexp{
		compile(`invalid opcode: 0000`),
		compile(`Kernel panic - not syncing`),
		compile(`unregister_netdevice: waiting for`),
		// Double fault can happen during handling of paging faults
		// if memory is badly corrupted. Also it usually happens
		// synchronously, which means that maybe the report is not corrupted.
		// But of course it can come from another CPU as well.
		compile(`PANIC: double fault`),
		compile(`Internal error:`),
	}
	// These pattern math kernel reports which are not bugs in itself but contain stack traces.
	// If we see them in the middle of another report, we know that the report is potentially corrupted.
	ctx.infoMessagesWithStack = [][]byte{
		[]byte("vmalloc: allocation failure:"),
		[]byte("FAULT_INJECTION: forcing a failure"),
		[]byte("FAULT_FLAG_ALLOW_RETRY missing"),
	}
	suppressions := []string{
		"panic: failed to start executor binary",
		"panic: executor failed: pthread_create failed",
		"panic: failed to create temp dir",
		"fatal error: unexpected signal during runtime execution", // presubmably OOM turned into SIGBUS
		"signal SIGBUS: bus error",                                // presubmably OOM turned into SIGBUS
		"SYZFAIL: SIGBUS",
		"Out of memory: Kill process .* \\(syz-executor\\)",
		"Out of memory: Kill process .* \\(sshd\\)",
		"Killed process .* \\(syz-executor\\)",
		"Killed process .* \\(sshd\\)",
		"lowmemorykiller: Killing 'syz-executor'",
		"lowmemorykiller: Killing 'sshd'",
		"INIT: PANIC: segmentation violation!",
		"\\*\\*\\* stack smashing detected \\*\\*\\*: terminated",
	}
	return ctx, suppressions, nil
}

const contextConsole = "console"

func (ctx *linux) ContainsCrash(output []byte) bool {
	return containsCrash(output, linuxOopses, ctx.ignores)
}

func (ctx *linux) Parse(output []byte) *Report {
	oops, startPos, context := ctx.findFirstOops(output)
	if oops == nil {
		return nil
	}
	for questionable := false; ; questionable = true {
		rep := &Report{
			Output:   output,
			StartPos: startPos,
		}
		endPos, reportEnd, report, prefix := ctx.findReport(output, oops, startPos, context, questionable)
		rep.EndPos = endPos
		title, corrupted, altTitles, format := extractDescription(report[:reportEnd], oops, linuxStackParams)
		if title == "" {
			prefix = nil
			report = output[rep.StartPos:rep.EndPos]
			title, corrupted, altTitles, format = extractDescription(report, oops, linuxStackParams)
			if title == "" {
				panic(fmt.Sprintf("non matching oops for %q context=%q in:\n%s\n",
					oops.header, context, report))
			}
		}
		rep.Title = title
		rep.AltTitles = altTitles
		rep.Corrupted = corrupted != ""
		rep.CorruptedReason = corrupted
		for _, line := range prefix {
			rep.Report = append(rep.Report, line...)
			rep.Report = append(rep.Report, '\n')
		}
		rep.reportPrefixLen = len(rep.Report)
		rep.Report = append(rep.Report, report...)
		rep.Type = TitleToCrashType(rep.Title)
		setExecutorInfo(rep)
		if !rep.Corrupted {
			rep.Corrupted, rep.CorruptedReason = isCorrupted(title, report, format)
		}
		if rep.CorruptedReason == corruptedNoFrames && context != contextConsole && !questionable {
			// We used to look at questionable frame with the following incentive:
			// """
			// Some crash reports have all frames questionable.
			// So if we get a corrupted report because there are no frames,
			// try again now looking at questionable frames.
			// Only do this if we have a real context (CONFIG_PRINTK_CALLER=y),
			// to be on the safer side. Without context it's too easy to use
			// a stray frame from a wrong context.
			// """
			// Most likely reports without proper stack traces were caused by a bug
			// in the unwinder and are now fixed in 187b96db5ca7 "x86/unwind/orc:
			// Fix unwind_get_return_address_ptr() for inactive tasks".
			// Disable trying to use questionable frames for now.
			useQuestionableFrames := false
			if useQuestionableFrames {
				continue
			}
		}
		return rep
	}
}

func (ctx *linux) findFirstOops(output []byte) (oops *oops, startPos int, context string) {
	for pos, next := 0, 0; pos < len(output); pos = next + 1 {
		next = bytes.IndexByte(output[pos:], '\n')
		if next != -1 {
			next += pos
		} else {
			next = len(output)
		}
		line := output[pos:next]
		for _, oops1 := range linuxOopses {
			if matchOops(line, oops1, ctx.ignores) {
				oops = oops1
				startPos = pos
				context = ctx.extractContext(line)
				return
			}
		}
	}
	return
}

// This method decides if the report prefix is already long enough to be cut on "Kernel panic - not
// syncing: panic_on_kmsan set ...".
func (ctx *linux) reportMinLines(oopsLine []byte) int {
	if bytes.Contains(oopsLine, []byte("BUG: KMSAN:")) {
		// KMSAN reports do not have the "Call trace" and some of the other lines which are
		// present e.g. in KASAN reports. So we use a lower threshold for them.
		return 16
	}
	return 22
}

// Yes, it is complex, but all state and logic are tightly coupled. It's unclear how to simplify it.
// nolint: gocyclo, gocognit
func (ctx *linux) findReport(output []byte, oops *oops, startPos int, context string, useQuestionable bool) (
	endPos, reportEnd int, report []byte, prefix [][]byte) {
	// Prepend 5 lines preceding start of the report,
	// they can contain additional info related to the report.
	maxPrefix := 5
	if ctx.taskContext.MatchString(context) {
		// If we have CONFIG_PRINTK_CALLER, we collect more b/c it comes from the same task.
		maxPrefix = 50
	}
	secondReportPos := 0
	textLines := 0
	skipText, cpuTraceback := false, false
	oopsLine := []byte{}
	for pos, next := 0, 0; pos < len(output); pos = next + 1 {
		next = bytes.IndexByte(output[pos:], '\n')
		if next != -1 {
			next += pos
		} else {
			next = len(output)
		}
		line := output[pos:next]
		context1 := ctx.extractContext(line)
		stripped, questionable := ctx.stripLinePrefix(line, context1, useQuestionable)
		if pos < startPos {
			if context1 == context && len(stripped) != 0 && !questionable {
				prefix = append(prefix, append([]byte{}, stripped...))
				if len(prefix) > maxPrefix {
					prefix = prefix[1:]
				}
			}
			continue
		}
		isOopsLine := pos == startPos
		if isOopsLine {
			oopsLine = line
		}

		for _, oops1 := range linuxOopses {
			if !matchOops(line, oops1, ctx.ignores) {
				if !isOopsLine && secondReportPos == 0 {
					for _, pattern := range ctx.infoMessagesWithStack {
						if bytes.Contains(line, pattern) {
							secondReportPos = pos
							break
						}
					}
				}
				continue
			}
			endPos = next
			if !isOopsLine && secondReportPos == 0 {
				if !matchesAny(line, ctx.reportStartIgnores) {
					secondReportPos = pos
				}
			}
		}
		if !isOopsLine && (questionable ||
			context1 != context && (!cpuTraceback || !ctx.cpuContext.MatchString(context1))) {
			continue
		}
		textLines++
		skipLine := skipText
		if bytes.Contains(line, []byte("Disabling lock debugging due to kernel taint")) {
			skipLine = true
		} else if bytes.Contains(line, []byte("Sending NMI from CPU")) {
			// If we are doing traceback of all CPUs, then we also need to preserve output
			// from other CPUs regardless of what is the current context.
			// Otherwise we will throw traceback away because it does not match the oops context.
			cpuTraceback = true
		} else if (bytes.Contains(line, []byte("Kernel panic - not syncing")) ||
			bytes.Contains(line, []byte("WARNING: possible circular locking dependency detected"))) &&
			textLines > ctx.reportMinLines(oopsLine) {
			// If panic_on_warn set, then we frequently have 2 stacks:
			// one for the actual report (or maybe even more than one),
			// and then one for panic caused by panic_on_warn. This makes
			// reports unnecessary long and the panic (current) stack
			// is always present in the actual report. So we strip the
			// panic message. However, we check that we have enough lines
			// before the panic, because sometimes we have, for example,
			// a single WARNING line without a stack and then the panic
			// with the stack.
			// Oops messages frequently induce possible deadlock reports
			// because oops reporting introduces unexpected locking chains.
			// So if we have enough of the actual oops, strip the deadlock message.
			skipText = true
			skipLine = true
		}
		if !isOopsLine && skipLine {
			continue
		}
		report = append(report, stripped...)
		report = append(report, '\n')
		if secondReportPos == 0 || context != "" && context != contextConsole {
			reportEnd = len(report)
		}
	}
	return
}

func (ctx *linux) stripLinePrefix(line []byte, context string, useQuestionable bool) ([]byte, bool) {
	if context == "" {
		return line, false
	}
	start := bytes.Index(line, []byte("] "))
	line = line[start+2:]
	if !bytes.Contains(line, ctx.eoi) {
		// x86_64 prefix.
		if ctx.questionableFrame.Match(line) {
			pos := bytes.Index(line, []byte(" ? "))
			return line[pos+2:], !useQuestionable
		}
		// PowerPC suffix.
		if bytes.HasSuffix(line, []byte(" (unreliable)")) {
			return line[:len(line)-13], !useQuestionable
		}
	}
	return line, false
}

func (ctx *linux) extractContext(line []byte) string {
	match := ctx.consoleOutputRe.FindSubmatchIndex(line)
	if match == nil {
		return ""
	}
	if match[2] == -1 {
		return contextConsole
	}
	return string(line[match[2]:match[3]])
}

func (ctx *linux) Symbolize(rep *Report) error {
	var symbFunc symbFuncCb
	if ctx.vmlinux != "" {
		symb := symbolizer.Make(ctx.config.target)
		defer symb.Close()
		symbFunc = func(bin string, pc uint64) ([]symbolizer.Frame, error) {
			return ctx.symbolizerCache.Symbolize(symb.Symbolize, bin, pc)
		}
	}
	if err := ctx.symbolize(rep, symbFunc); err != nil {
		return err
	}
	rep.Report = ctx.decompileOpcodes(rep.Report, rep)

	// Skip getting maintainers for Android fuzzing since the kernel source
	// directory structure is different.
	if ctx.config.vmType == "cuttlefish" || ctx.config.vmType == "proxyapp" {
		return nil
	}

	// We still do this even if we did not symbolize,
	// because tests pass in already symbolized input.
	rep.GuiltyFile = ctx.extractGuiltyFile(rep)
	if rep.GuiltyFile != "" {
		maintainers, err := ctx.getMaintainers(rep.GuiltyFile)
		if err != nil {
			return err
		}
		rep.Recipients = maintainers
	}
	return nil
}

type symbFuncCb = func(string, uint64) ([]symbolizer.Frame, error)

func (ctx *linux) symbolize(rep *Report, symbFunc symbFuncCb) error {
	var symbolized []byte
	prefix := rep.reportPrefixLen
	for _, line := range bytes.SplitAfter(rep.Report, []byte("\n")) {
		var newLine []byte
		parsed, ok := parseLinuxBacktraceLine(line)
		if ok {
			lines := []linuxBacktraceLine{parsed}
			if symbFunc != nil {
				lines = symbolizeLine(symbFunc, ctx, parsed)
			}
			for _, line := range lines {
				line.Name = demangle.Filter(line.Name, demangle.NoParams)
				newLine = append(newLine, line.Assemble()...)
			}
		} else {
			newLine = line
		}
		if prefix > len(symbolized) {
			prefix += len(newLine) - len(line)
		}
		symbolized = append(symbolized, newLine...)
	}
	oldReport := rep.Report
	rep.Report = symbolized
	oldPrefixLen := rep.reportPrefixLen
	rep.reportPrefixLen = prefix

	if len(rep.Report) > 0 && rep.reportPrefixLen > len(rep.Report) {
		panic(fmt.Sprintf("invalid reportPrefixLen after symbolize: prefix %d -> %d,"+
			"report len: %d -> %d, old report: %q",
			oldPrefixLen, rep.reportPrefixLen, len(oldReport), len(rep.Report), oldReport,
		))
	}
	return nil
}

type linuxBacktraceLine struct {
	// Fields and corresponding indices in the indices array.
	Name   string // 2:3
	Offset uint64 // 4:5
	Size   uint64 // 6:7
	// ... 8:9 is a ModName + its enclosing parentheses.
	ModName    string // 10:11
	BuildID    string // 12:13
	IsRipFrame bool
	// These fields are to be set externally.
	Inline   bool
	FileLine string
	// These fields are not to be modified outside of the type's methods.
	raw     []byte
	indices []int
}

func parseLinuxBacktraceLine(line []byte) (info linuxBacktraceLine, ok bool) {
	match := linuxSymbolizeRe.FindSubmatchIndex(line)
	if match == nil {
		return
	}
	info.raw = line
	info.indices = match
	info.Name = string(line[match[2]:match[3]])
	var err error
	info.Offset, err = strconv.ParseUint(string(line[match[4]:match[5]]), 16, 64)
	if err != nil {
		return
	}
	info.Size, err = strconv.ParseUint(string(line[match[6]:match[7]]), 16, 64)
	if err != nil {
		return
	}
	if match[10] != -1 && match[11] != -1 {
		info.ModName = string(line[match[10]:match[11]])
	}
	if match[12] != -1 && match[13] != -1 {
		info.BuildID = string(line[match[12]:match[13]])
	}
	info.IsRipFrame = linuxRipFrame.Match(line)
	return info, true
}

// Note that Assemble() ignores changes to Offset and Size (no reason as these are not updated anywhere).
func (line linuxBacktraceLine) Assemble() []byte {
	match := line.indices
	modified := append([]byte{}, line.raw...)
	if line.BuildID != "" {
		modified = replace(modified, match[8], match[9], []byte(" ["+line.ModName+"]"))
	}
	if line.FileLine != "" {
		modified = replace(modified, match[7], match[7], []byte(line.FileLine))
	}
	if line.Inline {
		end := match[7] + len(line.FileLine)
		modified = replace(modified, end, end, []byte(" [inline]"))
		modified = replace(modified, match[2], match[7], []byte(line.Name))
	} else {
		modified = replace(modified, match[2], match[3], []byte(line.Name))
	}
	return modified
}

func symbolizeLine(symbFunc func(bin string, pc uint64) ([]symbolizer.Frame, error), ctx *linux,
	parsed linuxBacktraceLine) []linuxBacktraceLine {
	symb := ctx.symbols[parsed.ModName][parsed.Name]
	if len(symb) == 0 {
		return []linuxBacktraceLine{parsed}
	}
	var funcStart uint64
	for _, s := range symb {
		if funcStart == 0 || int(parsed.Size) == s.Size {
			funcStart = s.Addr
		}
	}
	pc := funcStart + parsed.Offset
	if !parsed.IsRipFrame {
		// Usually we have return PCs, so we need to look at the previous instruction.
		// But RIP lines contain the exact faulting PC.
		pc--
	}
	var bin string
	for _, mod := range ctx.config.kernelModules {
		if mod.Name == parsed.ModName {
			bin = mod.Path
			break
		}
	}
	frames, err := symbFunc(bin, pc)
	if err != nil || len(frames) == 0 {
		return []linuxBacktraceLine{parsed}
	}
	var ret []linuxBacktraceLine
	for _, frame := range frames {
		path, _ := backend.CleanPath(frame.File, &ctx.kernelDirs, nil)
		copy := parsed
		copy.FileLine = fmt.Sprintf(" %v:%v", path, frame.Line)
		if frame.Inline {
			copy.Inline = true
			copy.Name = frame.Func
		}
		ret = append(ret, copy)
	}
	return ret
}

type parsedOpcodes struct {
	rawBytes       []byte
	decompileFlags DecompilerFlagMask
	offset         int
}

type decompiledOpcodes struct {
	opcodes           []DecompiledOpcode
	trappingOpcodeIdx int
	leftBytesCut      int
}

// processOpcodes converts a string representation of opcodes used by the Linux kernel into
// a sequence of the machine instructions, that surround the one that crashed the kernel.
// If the input does not start on a boundary of an instruction, it is attempted to adjust the
// strting position.
// The method returns an error if it did not manage to correctly decompile the opcodes or
// of the decompiled code is not of interest to the reader (e.g. it is a user-space code).
func (ctx *linux) processOpcodes(codeSlice string) (*decompiledOpcodes, error) {
	parsed, err := ctx.parseOpcodes(codeSlice)
	if err != nil {
		return nil, err
	}

	decompiled, err := ctx.decompileWithOffset(parsed)
	if err != nil {
		return nil, err
	}

	if linuxSkipTrapInstrRe.MatchString(decompiled.opcodes[decompiled.trappingOpcodeIdx].Instruction) {
		// For some reports (like WARNINGs) the trapping instruction is an intentionally
		// invalid instruction. Decompilation of such code only allows to see the
		// mechanism, through which the kernel implements such assertions and does not
		// aid in finding the real issue.
		return nil, fmt.Errorf("these opcodes are not of interest")
	}

	return decompiled, nil
}

func (ctx *linux) decompileWithOffset(parsed parsedOpcodes) (*decompiledOpcodes, error) {
	// It is not guaranteed that the fragment of opcodes starts exactly at the boundary
	// of a machine instruction. In order to simplify debugging process, we are trying
	// to find the right starting position.
	//
	// We iterate over a fixed number of left boundaries. The exact number of iterations
	// should strike a balance between the potential usefulness and the extra time needed
	// to invoke the decompiler.
	const opcodeAdjustmentLimit = 8

	var bestResult *decompiledOpcodes

	for leftCut := 0; leftCut <= parsed.offset && leftCut < opcodeAdjustmentLimit; leftCut++ {
		newBytes := parsed.rawBytes[leftCut:]
		newOffset := parsed.offset - leftCut
		instructions, err := DecompileOpcodes(newBytes, parsed.decompileFlags, ctx.target)
		if err != nil {
			return nil, err
		}

		// We only want to return the response, where there exists a decoded instruction that
		// perfectly aligns with the trapping instruction offset.
		// At the same time, we'll do out best to find a code listing that does not contain
		// unrecognized (bad) instuctions - this serves as an indicator of a valid result.

		hasBad := false
		trappingIdx := -1
		for idx, instruction := range instructions {
			if instruction.Offset == newOffset {
				trappingIdx = idx
			}
			if instruction.Offset >= newOffset {
				// Do not take into account instructions after the target offset. Once
				// decompiler begins to find the right boundary, we cannot improve them.
				break
			}
			hasBad = hasBad || instruction.IsBad
		}

		if trappingIdx < 0 {
			continue
		}

		if !hasBad || bestResult == nil {
			bestResult = &decompiledOpcodes{
				opcodes:           instructions,
				trappingOpcodeIdx: trappingIdx,
				leftBytesCut:      leftCut,
			}
			if !hasBad {
				// The best offset is already found.
				break
			}
		}
	}
	if bestResult == nil {
		return nil, fmt.Errorf("unable to align decompiled code and the trapping instruction offset")
	}
	return bestResult, nil
}

func (ctx *linux) parseOpcodes(codeSlice string) (parsedOpcodes, error) {
	width := 0
	bytes := []byte{}
	trapOffset := -1
	for _, part := range strings.Split(strings.TrimSpace(codeSlice), " ") {
		if part == "" || len(part)%2 != 0 {
			return parsedOpcodes{}, fmt.Errorf("invalid opcodes string %#v", part)
		}

		// Check if this is a marker of a trapping instruction.
		if part[0] == '(' || part[0] == '<' {
			if trapOffset >= 0 {
				return parsedOpcodes{}, fmt.Errorf("invalid opcodes string: multiple trap intructions")
			}
			trapOffset = len(bytes)

			if len(part) < 3 {
				return parsedOpcodes{}, fmt.Errorf("invalid opcodes string: invalid trap opcode")
			}
			part = part[1 : len(part)-1]
		}

		if width == 0 {
			width = len(part) / 2
		}

		number, err := strconv.ParseUint(part, 16, 64)
		if err != nil {
			return parsedOpcodes{}, fmt.Errorf("invalid opcodes string: failed to parse %#v", part)
		}

		extraBytes := make([]byte, width)
		switch len(extraBytes) {
		case 1:
			extraBytes[0] = byte(number)
		case 2:
			ctx.target.HostEndian.PutUint16(extraBytes, uint16(number))
		case 4:
			ctx.target.HostEndian.PutUint32(extraBytes, uint32(number))
		case 8:
			ctx.target.HostEndian.PutUint64(extraBytes, number)
		default:
			return parsedOpcodes{}, fmt.Errorf("invalid opcodes string: invalid width %v", width)
		}
		bytes = append(bytes, extraBytes...)
	}

	if trapOffset < 0 {
		return parsedOpcodes{}, fmt.Errorf("invalid opcodes string: no trapping instructions")
	}

	var flags DecompilerFlagMask
	if ctx.target.Arch == targets.ARM && width == 2 {
		flags |= FlagForceArmThumbMode
	}
	return parsedOpcodes{
		rawBytes:       bytes,
		decompileFlags: flags,
		offset:         trapOffset,
	}, nil
}

// decompileOpcodes detects the most meaningful "Code: " lines from the report, decompiles
// them and appends a human-readable listing to the end of the report.
func (ctx *linux) decompileOpcodes(text []byte, report *Report) []byte {
	if report.Type == crash.Hang {
		// Even though Hang reports do contain the Code: section, there's no point in
		// decompiling that. So just return the text.
		return text
	}
	// Iterate over all "Code: " lines and pick the first that could be decompiled
	// that might be of interest to the user.
	var decompiled *decompiledOpcodes
	lines := lines(text)
	for i, line := range lines {
		var prevLine []byte
		if i > 0 {
			prevLine = lines[i-1]
		}
		// We want to avoid decompiling code from user-space as it is not of big interest during
		// debugging kernel problems.
		// For now this check only works for x86/amd64, but Linux on other architectures supported
		// by syzkaller does not seem to include user-space code in its oops messages.
		if linuxUserSegmentRe.Match(prevLine) {
			continue
		}
		match := linuxCodeRe.FindSubmatch(line)
		if match == nil {
			continue
		}
		decompiledLine, err := ctx.processOpcodes(string(match[1]))
		if err != nil {
			continue
		}
		decompiled = decompiledLine
		break
	}

	if decompiled == nil {
		return text
	}

	skipInfo := ""
	if decompiled.leftBytesCut > 0 {
		skipInfo = fmt.Sprintf(", %v bytes skipped", decompiled.leftBytesCut)
	}

	// The decompiled instructions are intentionally put to the bottom of the report instead
	// being inlined below the corresponding "Code:" line. The intent is to continue to keep
	// the most important information at the top of the report, so that it is visible from
	// the syzbot dashboard without scrolling.
	headLine := fmt.Sprintf("----------------\nCode disassembly (best guess)%v:\n", skipInfo)
	text = append(text, headLine...)

	for idx, opcode := range decompiled.opcodes {
		line := opcode.FullDescription
		if idx == decompiled.trappingOpcodeIdx {
			line = fmt.Sprintf("*%s <-- trapping instruction\n", line[1:])
		} else {
			line += "\n"
		}
		text = append(text, line...)
	}
	return text
}

func (ctx *linux) extractGuiltyFile(rep *Report) string {
	return ctx.extractGuiltyFileRaw(rep.Title, rep.Report[rep.reportPrefixLen:])
}

func (ctx *linux) extractGuiltyFileRaw(title string, report []byte) string {
	if strings.HasPrefix(title, "INFO: rcu detected stall") {
		// Special case for rcu stalls.
		// There are too many frames that we want to skip before actual guilty frames,
		// we would need to ignore too many files and that would be fragile.
		// So instead we try to extract guilty file starting from the known
		// interrupt entry point first.
		for _, interruptEnd := range []string{"apic_timer_interrupt+0x",
			"el1h_64_irq+0x", "Exception stack"} {
			if pos := bytes.Index(report, []byte(interruptEnd)); pos != -1 {
				if file := ctx.extractGuiltyFileImpl(report[pos:]); file != "" {
					return file
				}
			}
		}
	}
	return ctx.extractGuiltyFileImpl(report)
}

func (ctx *linux) extractGuiltyFileImpl(report []byte) string {
	// Extract the first possible guilty file.
	guilty := ""
	var line []byte
	lines := lines(report)
	for len(lines) > 0 {
		line, lines = lines[0], lines[1:]
		match := filenameRe.FindSubmatch(line)
		if match == nil {
			continue
		}
		file := match[1]
		if guilty == "" {
			// Avoid producing no guilty file at all, otherwise we mail the report to nobody.
			// It's unclear if it's better to return the first one or the last one.
			// So far the only test we have has only one file anyway.
			guilty = string(file)
		}

		if matchesAny(file, ctx.guiltyFileIgnores) || ctx.guiltyLineIgnore.Match(line) {
			continue
		}
		guilty = filepath.Clean(string(file))
		break
	}

	// Search for deeper filepaths in the stack trace below the first possible guilty file.
	deepestPath := filepath.Dir(guilty)
	for len(lines) > 0 {
		line, lines = lines[0], lines[1:]
		match := filenameRe.FindSubmatch(line)
		if match == nil {
			continue
		}
		file := match[1]
		if matchesAny(file, ctx.guiltyFileIgnores) || ctx.guiltyLineIgnore.Match(line) {
			continue
		}
		clean := filepath.Clean(string(file))

		// Check if the new path has *both* the same directory prefix *and* a deeper suffix.
		if strings.HasPrefix(clean, deepestPath) {
			suffix := strings.TrimPrefix(clean, deepestPath)
			if deeperPathRe.Match([]byte(suffix)) {
				guilty = clean
				deepestPath = filepath.Dir(guilty)
			}
		}
	}

	return guilty
}

func (ctx *linux) getMaintainers(file string) (vcs.Recipients, error) {
	if ctx.kernelDirs.Src == "" {
		return nil, nil
	}
	return GetLinuxMaintainers(ctx.kernelDirs.Src, file)
}

func GetLinuxMaintainers(kernelSrc, file string) (vcs.Recipients, error) {
	mtrs, err := getMaintainersImpl(kernelSrc, file, false)
	if err != nil {
		return nil, err
	}
	if len(mtrs) <= 1 {
		mtrs, err = getMaintainersImpl(kernelSrc, file, true)
		if err != nil {
			return nil, err
		}
	}
	return mtrs, nil
}

func getMaintainersImpl(kernelSrc, file string, blame bool) (vcs.Recipients, error) {
	// See #1441 re --git-min-percent.
	args := []string{"--git-min-percent=15"}
	if blame {
		args = append(args, "--git-blame")
	}
	args = append(args, "-f", file)
	script := filepath.FromSlash("scripts/get_maintainer.pl")
	output, err := osutil.RunCmd(time.Minute, kernelSrc, script, args...)
	if err != nil {
		return nil, err
	}
	return vcs.ParseMaintainersLinux(output), nil
}

func isCorrupted(title string, report []byte, format oopsFormat) (bool, string) {
	// Check for common title corruptions.
	for _, re := range linuxCorruptedTitles {
		if re.MatchString(title) {
			return true, "title matches corrupted regexp"
		}
	}
	// If the report hasn't matched any of the oops titles, don't mark it as corrupted.
	if format.title == nil {
		return false, ""
	}
	if format.noStackTrace {
		return false, ""
	}
	// When a report contains 'Call Trace', 'backtrace', 'Allocated' or 'Freed' keywords,
	// it must also contain at least a single stack frame after each of them.
	hasStackTrace := false
	for _, key := range linuxStackParams.stackStartRes {
		match := key.FindSubmatchIndex(report)
		if match == nil {
			continue
		}
		frames := lines(report[match[0]:])
		if len(frames) < 4 {
			return true, "call trace is missed"
		}
		corrupted := true
		frames = frames[1:]
		// Check that at least one of the next few lines contains a frame.
	outer:
		for i := 0; i < 15 && i < len(frames); i++ {
			for _, key1 := range linuxStackParams.stackStartRes {
				// Next stack trace starts.
				if key1.Match(frames[i]) {
					break outer
				}
			}
			if bytes.Contains(frames[i], []byte("(stack is not available)")) ||
				matchesAny(frames[i], linuxStackParams.frameRes) {
				hasStackTrace = true
				corrupted = false
				break
			}
		}
		if corrupted {
			return true, "no frames in a stack trace"
		}
	}
	if !hasStackTrace {
		return true, "no stack trace in report"
	}
	return false, ""
}

var syzLinuxCommRe = regexp.MustCompile(` Comm: syz\.(\d+)\.(\d+) `)

func setExecutorInfo(rep *Report) {
	match := syzLinuxCommRe.FindSubmatch(rep.Report)
	if match == nil {
		return
	}
	info := &ExecutorInfo{}
	var err error
	info.ProcID, err = strconv.Atoi(string(match[1]))
	if err != nil {
		return
	}
	info.ExecID, err = strconv.Atoi(string(match[2]))
	if err != nil {
		return
	}
	rep.Executor = info
}

func linuxStallFrameExtractor(frames []string) (string, int) {
	// During rcu stalls and cpu lockups kernel loops in some part of code,
	// usually across several functions. When the stall is detected, traceback
	// points to a random stack within the looping code. We generally take
	// the top function in the stack (with few exceptions) as the bug identity.
	// As the result stalls with the same root would produce multiple reports
	// in different functions, which is bad.
	// Instead we identify a representative function deeper in the stack.
	// For most syscalls it can be the syscall entry function (e.g. SyS_timer_create).
	// However, for highly discriminated functions syscalls like ioctl/read/write/connect
	// we take the previous function (e.g. for connect the one that points to exact
	// protocol, or for ioctl the one that is related to the device).
	prev, prevIdx := frames[0], 0
	for i, frame := range frames {
		if matchesAny([]byte(frame), linuxStallAnchorFrames) {
			if strings.Contains(frame, "smp_call_function") {
				// In this case we want this function rather than the previous one
				// (there can be several variations on the next one).
				prev = "smp_call_function"
				prevIdx = i
			}
			return prev, prevIdx
		}
		prev, prevIdx = frame, i
	}
	return "", -1
}

func linuxHangTaskFrameExtractor(frames []string) (string, int) {
	// The problem with task hung reports is that they manifest at random victim stacks,
	// rather at the root cause stack. E.g. if there is something wrong with RCU subsystem,
	// we are getting hangs all over the kernel on all synchronize_* calls.
	// So before resotring to the common logic of skipping some common frames,
	// we look for 2 common buckets: hangs on synchronize_rcu and hangs on rtnl_lock
	// and group these together.
	const synchronizeRCU = "synchronize_rcu"
	anchorFrames := map[string]string{
		"rtnl_lock":         "",
		"synchronize_rcu":   synchronizeRCU,
		"synchronize_srcu":  synchronizeRCU,
		"synchronize_net":   synchronizeRCU,
		"synchronize_sched": synchronizeRCU,
	}
	for i, frame := range frames {
		for anchor, replacement := range anchorFrames {
			if strings.Contains(frame, anchor) {
				if replacement != "" {
					frame = replacement
				}
				return frame, i
			}
		}
	}
	skip := []string{"sched", "_lock", "_slowlock", "down", "rwsem", "completion", "kthread",
		"wait", "synchronize", "context_switch", "__switch_to", "cancel_delayed_work",
		"rcu_barrier"}
nextFrame:
	for i, frame := range frames {
		for _, ignore := range skip {
			if strings.Contains(frame, ignore) {
				continue nextFrame
			}
		}
		return frame, i
	}
	return "", -1
}

var linuxStallAnchorFrames = []*regexp.Regexp{
	// Various generic functions that dispatch work.
	// We also include some of their callers, so that if some names change
	// we don't skip whole stacks and proceed parsing the next one.
	compile("process_one_work"),  // workqueue callback
	compile("do_syscall_"),       // syscall entry
	compile("do_fast_syscall_"),  // syscall entry
	compile("sysenter_dispatch"), // syscall entry
	compile("tracesys_phase2"),   // syscall entry
	compile("el0_svc_handler"),   // syscall entry
	compile("invoke_syscall"),    // syscall entry
	compile("ret_fast_syscall"),  // arm syscall entry
	compile("netif_receive_skb"), // net receive entry point
	compile("do_softirq"),
	compile("call_timer_fn"),
	compile("_run_timers"),
	compile("run_timer_softirq"),
	compile("hrtimer_run"),
	compile("run_ksoftirqd"),
	compile("smpboot_thread_fn"),
	compile("^kthread$"),
	compile("start_secondary"),
	compile("cpu_startup_entry"),
	compile("ret_from_fork"),
	// Important discriminated syscalls (file_operations callbacks, etc):
	compile("vfs_write"),
	compile("vfs_read"),
	compile("vfs_iter_read"),
	compile("vfs_iter_write"),
	compile("do_iter_read"),
	compile("do_iter_write"),
	compile("call_read_iter"),
	compile("call_write_iter"),
	compile("new_sync_read"),
	compile("new_sync_write"),
	compile("vfs_ioctl"),
	compile("ksys_ioctl"), // vfs_ioctl may be inlined
	compile("compat_ioctl"),
	compile("compat_sys_ioctl"),
	compile("blkdev_driver_ioctl"),
	compile("blkdev_ioctl"),
	compile("^call_read_iter"),
	compile("^call_write_iter"),
	compile("do_iter_readv_writev"),
	compile("^call_mmap"),
	compile("mmap_region"),
	compile("do_mmap"),
	compile("do_dentry_open"),
	compile("vfs_open"),
	// Socket operations:
	compile("^sock_sendmsg"),
	compile("^sock_recvmsg"),
	compile("^sock_release"),
	compile("^__sock_release"),
	compile("^setsockopt$"),
	compile("kernel_setsockopt"),
	compile("sock_common_setsockopt"),
	compile("^listen$"),
	compile("kernel_listen"),
	compile("sk_common_release"),
	compile("^sock_mmap"),
	compile("^accept$"),
	compile("kernel_accept"),
	compile("^sock_do_ioctl"),
	compile("^sock_ioctl"),
	compile("^compat_sock_ioctl"),
	compile("^nfnetlink_rcv_msg"),
	compile("^rtnetlink_rcv_msg"),
	compile("^netlink_dump"),
	compile("^(sys_)?(socketpair|connect|ioctl)"),
	// Page fault entry points:
	compile("__do_fault"),
	compile("do_page_fault"),
	compile("^page_fault$"),
	// exit_to_usermode_loop callbacks:
	compile("__fput"),
	compile("task_work_run"),
	compile("exit_to_usermode"),
	compile("smp_call_function"),
	compile("tasklet_action"),
	compile("tasklet_hi_action"),
}

// nolint: lll
var (
	linuxSymbolizeRe     = regexp.MustCompile(`(?:\[\<(?:(?:0x)?[0-9a-f]+)\>\])?[ \t]+\(?(?:[0-9]+:)?([a-zA-Z0-9_.]+)\+0x([0-9a-f]+)/0x([0-9a-f]+)( ?\[([a-zA-Z0-9_.]+)( .*)?\])?\)?`)
	linuxRipFrame        = compile(`(?:IP|NIP|pc |PC is at):? (?:(?:[0-9]+:)?(?:{{PC}} +){0,2}{{FUNC}}|(?:[0-9]+:)?0x[0-9a-f]+|(?:[0-9]+:)?{{PC}} +\[< *\(null\)>\] +\(null\)|[0-9]+: +\(null\))`)
	linuxCallTrace       = compile(`(?:Call (?:T|t)race:)|(?:Backtrace:)`)
	linuxCodeRe          = regexp.MustCompile(`(?m)^\s*Code\:\s+((?:[A-Fa-f0-9\(\)\<\>]{2,8}\s*)*)\s*$`)
	linuxSkipTrapInstrRe = regexp.MustCompile(`^ud2|brk\s+#0x800$`)
	linuxUserSegmentRe   = regexp.MustCompile(`^RIP:\s+0033:`)
)

var linuxCorruptedTitles = []*regexp.Regexp{
	// Sometimes timestamps get merged into the middle of report description.
	regexp.MustCompile(`\[ *[0-9]+\.[0-9]+\]`),
}

var linuxStackParams = &stackParams{
	stackStartRes: []*regexp.Regexp{
		regexp.MustCompile(`Call (?:T|t)race`),
		regexp.MustCompile(`Allocated:`),
		regexp.MustCompile(`Allocated by task [0-9]+:`),
		regexp.MustCompile(`Freed:`),
		regexp.MustCompile(`Freed by task [0-9]+:`),
		// Match 'backtrace:', but exclude 'stack backtrace:'
		regexp.MustCompile(`[^k] backtrace:`),
		regexp.MustCompile(`Backtrace:`),
		regexp.MustCompile(`Uninit was stored to memory at`),
	},
	frameRes: []*regexp.Regexp{
		compile("^ *(?:{{PC}} ){0,2}{{FUNC}}"),
		// Arm is totally different.
		// Extract both current and next frames. This is needed for the top
		// frame which is present only in LR register which we don't parse.
		compile(`^ *{{PC}} \(([a-zA-Z0-9_.]+)\) from {{PC}} \({{FUNC}}`),
	},
	skipPatterns: []string{
		"__sanitizer",
		"__asan",
		"kasan",
		"hwasan",
		"__msan",
		"kmsan",
		"kcsan_setup_watchpoint",
		"check_memory_region",
		"check_heap_object",
		"check_object",
		"read_word_at_a_time",
		"(read|write)_once_.*nocheck",
		"print_address_description",
		"panic",
		"invalid_op",
		"report_bug",
		"fixup_bug",
		"print_report",
		"print_usage_bug",
		"do_error",
		"invalid_op",
		`_trap$|do_trap`,
		"show_stack",
		"dump_stack",
		"walk_stack",
		"dump_backtrace",
		"warn_slowpath",
		"warn_alloc",
		"warn_bogus",
		"__warn",
		"alloc_page",
		"k?v?(?:m|z|c)alloc",
		"krealloc",
		"kmem_cache",
		"allocate_slab",
		"__alloc_frozen_pages_noprof",
		"folio_(?:alloc|unlock)",
		"filemap_alloc_folio",
		"__filemap_get_folio",
		"find_or_create_page",
		"do_read_cache_folio",
		"read_cache_page",
		"pagecache_get_page",
		"grab_cache_page_write_begin",
		"slab_",
		"debug_object",
		"timer_is_static_object",
		"work_is_static_object",
		"__might_fault",
		"print_unlock",
		"imbalance_bug",
		"lockdep",
		"bh_enable",
		"bh_disable",
		"perf_trace",
		"lock_acquire",
		"lock_release",
		"lock_class",
		"mark_lock",
		"(reacquire|mark)_held_locks",
		"raw_spin_rq",
		"spin_lock",
		"spin_trylock",
		"spin_unlock",
		"read_lock",
		"read_trylock",
		"write_lock",
		"write_trylock",
		"read_unlock",
		"write_unlock",
		"^down$",
		"down_read",
		"down_write",
		"down_read_trylock",
		"down_write_trylock",
		"down_trylock",
		"up_read",
		"up_write",
		"^mutex_",
		"^__mutex_",
		"^rt_mutex_",
		"owner_on_cpu",
		"osq_lock",
		"osq_unlock",
		"atomic(64)?_(dec|inc|read|set|or|xor|and|add|sub|fetch|xchg|cmpxchg|try)",
		"(set|clear|change|test)_bit",
		"__wake_up",
		"^refcount_",
		"^kref_",
		"ref_tracker",
		"seqprop_assert",
		"memcpy",
		"memcmp",
		"memset",
		"memchr",
		"memmove",
		"memdup",
		"strcmp",
		"strncmp",
		"strcpy",
		"strlcpy",
		"strncpy",
		"strscpy",
		"strlen",
		"strstr",
		"strnstr",
		"strnlen",
		"strchr",
		"strdup",
		"strndup",
		"copy_to_user",
		"copy_from_user",
		"copy_to_iter",
		"copy_from_iter",
		"copy_page_to_iter",
		"copy_page_from_iter",
		"copy_folio_to_iter",
		"^copyin$",
		"^copyout$",
		"put_user",
		"get_user",
		"might_fault",
		"might_sleep",
		"list_add",
		"list_del",
		"list_replace",
		"list_move",
		"list_splice",
		"^rb_",
		"^__rb_",
		"_indirect_thunk_", // retpolines
		"string",
		"pointer",
		"snprintf",
		"scnprintf",
		"kasprintf",
		"kvasprintf",
		"printk",
		"va_format",
		"dev_info",
		"dev_notice",
		"dev_warn",
		"dev_err",
		"dev_alert",
		"dev_crit",
		"dev_emerg",
		"program_check_exception",
		"program_check_common",
		"del_timer",
		"flush_work",
		"__cancel_work_timer",
		"cancel_work_sync",
		"try_to_grab_pending",
		"flush_workqueue",
		"drain_workqueue",
		"destroy_workqueue",
		"queue_work",
		"finish_wait",
		"kthread_stop",
		"kobject_",
		"add_uevent_var",
		"get_device_parent",
		"device_add",
		"device_del",
		"device_unregister",
		"device_destroy",
		"device_release",
		"devres_release_all",
		"hwrng_unregister",
		"i2c_del_adapter",
		"__unregister_client",
		"device_for_each_child",
		"rollback_registered",
		"unregister_netdev",
		"sysfs_remove",
		"device_remove_file",
		"tty_unregister_device",
		"dummy_urb_enqueue",
		"usb_kill_urb",
		"usb_kill_anchored_urbs",
		"usb_control_msg",
		"usb_hcd_submit_urb",
		"usb_submit_urb",
		"^complete$",
		"wait_for_completion",
		"^kv?free$",
		"kfree_skb",
		"readb$",
		"readw$",
		"readl$",
		"readq$",
		"writeb$",
		"writew$",
		"writel$",
		"writeq$",
		"logic_in",
		"logic_out",
		"^crc\\d+",
		"crc_itu_t",
		"__might_resched",
		"assertfail",
		"^iput$",
		"^iput_final$",
		"^ihold$",
		"hex_dump_to_buffer",
		"print_hex_dump",
		"^klist_",
		"(trace|lockdep)_(hard|soft)irq",
		"^(un)?lock_page",
		"stack_trace_consume_entry",
		"arch_stack_walk",
		"stack_trace_save",
		"insert_work",
		"__queue_delayed_work",
		"queue_delayed_work_on",
		"ida_free",
		// arm64 translation exception handling path.
		"do_(kernel|translation)_fault",
		"do_mem_abort",
		"el1_abort",
		"el1h_64_sync(?:_handler)?",
		"print_tainted",
		"xas_(?:start|load|find)",
		"find_lock_entries",
		"truncate_inode_pages_range",
		"__phys_addr",
		"__fortify_report",
		"cleanup_srcu_struct",
		"rhashtable_lookup",
		"extract_(user|iter)_to_sg",
		"drop_nlink",
		"^get_taint$",
		"^put_device$",
		"lock_timer_base",
		"__timer_delete_sync",
		"sk_stop_timer_sync",
		"__mod_timer",
	},
	corruptedLines: []*regexp.Regexp{
		// Fault injection stacks are frequently intermixed with crash reports.
		// Note: the actual symbol can have all kinds of weird suffixes like ".isra.7", ".cold" or ".isra.56.cold.74".
		compile(`^( \[\<?(?:0x)?[0-9a-f]+\>?\])? should_fail(slab)?(\.[a-z0-9.]+)?\+0x`),
	},
	stripFramePrefixes: []string{
		"SYSC_",
		"SyS_",
		"sys_",
		"__x64_",
		"__ia32_",
		"__arm64_",
		"____sys_",
		"___sys_",
		"__sys_",
		"__se_",
		"__se_sys_",
		"__do_sys_",
		"compat_SYSC_",
		"compat_SyS_",
		"ksys_",
	},
}

func warningStackFmt(skip ...string) *stackFmt {
	return &stackFmt{
		// In newer kernels WARNING traps and actual stack starts after invalid_op frame,
		// older kernels just print stack.
		parts: []*regexp.Regexp{
			// x86_64 warning stack starts with "RIP:" line,
			// while powerpc64 starts with "--- interrupt:".
			compile("(?:" + linuxRipFrame.String() + "|--- interrupt: [0-9]+ at {{FUNC}})"),
			parseStackTrace,
		},
		parts2: []*regexp.Regexp{
			linuxCallTrace,
			parseStackTrace,
		},
		skip: skip,
	}
}

// nolint: lll
var linuxOopses = append([]*oops{
	{
		[]byte("BUG:"),
		[]oopsFormat{
			{
				title:  compile("BUG: KASAN:"),
				report: compile("BUG: KASAN: ([a-z\\-]+) in {{FUNC}}(?:.*\\n)+?.*(Read|Write) (?:of size|at addr) (?:[0-9a-f]+)"),
				fmt:    "KASAN: %[1]v %[3]v in %[4]v",
				alt:    []string{"bad-access in %[4]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						compile("BUG: KASAN: (?:[a-z\\-]+) in {{FUNC}}"),
						linuxCallTrace,
						parseStackTrace,
					},
					// These frames are present in KASAN_HW_TAGS reports.
					skip: []string{"kernel_fault", "tag_check", "mem_abort", "^el1_", "^el1h_"},
				},
			},
			{
				title:  compile("BUG: KASAN:"),
				report: compile("BUG: KASAN: (?:double-free or invalid-free|double-free|invalid-free) in {{FUNC}}"),
				fmt:    "KASAN: invalid-free in %[2]v",
				alt:    []string{"invalid-free in %[2]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						compile("BUG: KASAN: (?:double-free or invalid-free|double-free|invalid-free) in {{FUNC}}"),
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"slab_", "kfree", "vunmap", "vfree"},
				},
			},
			{
				title: compile("BUG: KASAN: ([a-z\\-]+) on address(?:.*\\n)+?.*(Read|Write) of size ([0-9]+)"),
				fmt:   "KASAN: %[1]v %[2]v",
			},
			{
				title:     compile("BUG: KASAN: (.*)"),
				fmt:       "KASAN: %[1]v",
				corrupted: true,
			},
			{
				title:  compile("BUG: KMSAN: kernel-usb-infoleak"),
				report: compile("BUG: KMSAN: kernel-usb-infoleak in {{FUNC}}"),
				fmt:    "KMSAN: kernel-usb-infoleak in %[2]v",
				alt:    []string{"KMSAN origin in %[3]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						parseStackTrace,
						compile("(Local variable .* created at:|Uninit was created at:)"),
						parseStackTrace,
					},
					skip: []string{"alloc_skb", "usb_submit_urb", "usb_start_wait_urb", "usb_bulk_msg", "usb_interrupt_msg", "usb_control_msg"},
				},
				noStackTrace: true,
			},
			{
				title:  compile("BUG: KMSAN:"),
				report: compile("BUG: KMSAN: ([a-z\\-]+) in {{FUNC}}"),
				fmt:    "KMSAN: %[1]v in %[3]v",
				alt: []string{
					"bad-access in %[3]v",
				},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						parseStackTrace,
						compile("(Local variable .* created at:|Uninit was created at:)"),
						parseStackTrace,
					},
					skip: []string{"alloc_skb", "netlink_ack", "netlink_rcv_skb"},
				},
				noStackTrace: true,
			},
			{
				title:        compile("BUG: KCSAN: data-race"),
				report:       compile("BUG: KCSAN: (.*)"),
				fmt:          "KCSAN: %[1]v",
				noStackTrace: true,
			},
			{
				title:        compile("BUG: KCSAN:"),
				report:       compile("BUG: KCSAN: (.*)"),
				fmt:          "KCSAN: %[1]v",
				noStackTrace: true,
			},
			{
				title: compile("BUG: KFENCE: (use-after-free|out-of-bounds) (read|write) in {{FUNC}}"),
				fmt:   "KFENCE: %[1]v %[2]v in %[4]v",
				alt:   []string{"bad-access in %[4]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						compile("BUG: KFENCE: (?:[a-z\\- ]+) in {{FUNC}}"),
						parseStackTrace,
					},
				},
			},
			{
				title:        compile("BUG: KFENCE: invalid free in {{FUNC}}"),
				fmt:          "KFENCE: invalid free in %[2]v",
				alt:          []string{"invalid-free in %[2]v"},
				noStackTrace: true,
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						compile("BUG: KFENCE: (?:[a-z\\- ]+) in {{FUNC}}"),
						parseStackTrace,
					},
				},
			},
			{
				title: compile("BUG: KFENCE: invalid (read|write) in {{FUNC}}"),
				fmt:   "KFENCE: invalid %[1]v in %[3]v",
				alt:   []string{"bad-access in %[3]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						compile("BUG: KFENCE: (?:[a-z\\- ]+) in {{FUNC}}"),
						parseStackTrace,
					},
				},
			},
			{
				title:        compile("BUG: KFENCE: memory corruption in {{FUNC}}"),
				fmt:          "KFENCE: memory corruption in %[2]v",
				noStackTrace: true,
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						compile("BUG: KFENCE: (?:[a-z\\- ]+) in {{FUNC}}"),
						parseStackTrace,
					},
				},
			},
			{
				title: compile("BUG: (?:unable to handle kernel paging request|unable to handle page fault for address|Unable to handle kernel data access)"),
				fmt:   "BUG: unable to handle kernel paging request in %[1]v",
				alt:   []string{"bad-access in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
			{
				title: compile("BUG: (?:unable to handle kernel NULL pointer dereference|kernel NULL pointer dereference|Kernel NULL pointer dereference)"),
				fmt:   "BUG: unable to handle kernel NULL pointer dereference in %[1]v",
				alt:   []string{"bad-access in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
			{
				// Sometimes with such BUG failures, the second part of the header doesn't get printed
				// or gets corrupted, because kernel prints it as two separate printk() calls.
				title:     compile("BUG: (?:unable to handle kernel|Unable to handle kernel)"),
				fmt:       "BUG: unable to handle kernel",
				corrupted: true,
			},
			{
				title: compile("BUG: (spinlock|rwlock) (lockup suspected|already unlocked|recursion" +
					"|cpu recursion|bad magic|wrong owner|wrong CPU|trylock failure on UP)"),
				fmt: "BUG: %[1]v %[2]v in %[3]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"spin_", "_lock", "_unlock"},
				},
			},
			{
				title: compile("BUG: soft lockup"),
				fmt:   "BUG: soft lockup in %[1]v",
				alt:   []string{"stall in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
						linuxCallTrace,
						parseStackTrace,
					},
					extractor: linuxStallFrameExtractor,
				},
			},
			{
				title:  compile("BUG: .*still has locks held!"),
				report: compile("BUG: .*still has locks held!(?:.*\\n)+?.*{{PC}} +{{FUNC}}"),
				fmt:    "BUG: still has locks held in %[1]v",
			},
			{
				title: compile("BUG: scheduling while atomic"),
				fmt:   "BUG: scheduling while atomic in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"schedule"},
				},
			},
			{
				title:        compile("BUG: lock held when returning to user space"),
				report:       compile("BUG: lock held when returning to user space(?:.*\\n)+?.*leaving the kernel with locks still held(?:.*\\n)+?.*at: (?:{{PC}} +)?{{FUNC}}"),
				fmt:          "BUG: lock held when returning to user space in %[1]v",
				noStackTrace: true,
			},
			{
				title: compile("BUG: bad unlock balance detected!"),
				fmt:   "BUG: bad unlock balance in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						compile("{{PC}} +{{FUNC}}"),
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
			{
				title:  compile("BUG: held lock freed!"),
				report: compile("BUG: held lock freed!(?:.*\\n)+?.*{{PC}} +{{FUNC}}"),
				fmt:    "BUG: held lock freed in %[1]v",
			},
			{
				title:        compile("BUG: Bad rss-counter state"),
				fmt:          "BUG: Bad rss-counter state",
				noStackTrace: true,
			},
			{
				title:        compile("BUG: non-zero nr_ptes on freeing mm"),
				fmt:          "BUG: non-zero nr_ptes on freeing mm",
				noStackTrace: true,
			},
			{
				title:        compile("BUG: non-zero nr_pmds on freeing mm"),
				fmt:          "BUG: non-zero nr_pmds on freeing mm",
				noStackTrace: true,
			},
			{
				// Kernel includes filesystem type and block device name into the message.
				// We used to include them, but block devices are plain harmful (loop0/1/2),
				// and filesystem type also leads to duplicates. So now we exclude them.
				title:  compile("BUG: Dentry .* still in use"),
				report: compile("BUG: Dentry .* still in use \\([0-9]+\\) \\[(unmount) of ([^\\]]+)\\]"),
				fmt:    "BUG: Dentry still in use in %[1]v",
				alt:    []string{"BUG: Dentry still in use [%[1]v of %[2]v]"},
			},
			{
				title: compile("BUG: Bad page (state|cache)"),
				fmt:   "BUG: Bad page %[1]v in %[2]v",
				stack: &stackFmt{
					// TODO: on arm64, for some reason we don't see the page origin backtrace.
					// We see the stack trace where the bug was detected, but we consider it to be
					// not sufficient to reliably group crashes.
					// So Bad page reports on arm64 for now will end up marked as corrupted.
					parts: []*regexp.Regexp{
						compile(`page last allocated`),
						parseStackTrace,
					},
					skip: []string{"(free|put|get|update|release)_page",
						"free_unref", "^_*folio", "truncate_inode_pages",
						"page_frag_free", "alloc", "vmap", "page_owner"},
				},
			},
			{
				title: compile("BUG: Bad page map"),
				fmt:   "BUG: Bad page map",
			},
			{
				title:        compile("BUG: workqueue lockup"),
				fmt:          "BUG: workqueue lockup",
				noStackTrace: true,
			},
			{
				title: compile("BUG: sleeping function called from invalid context at (.*)"),
				fmt:   "BUG: sleeping function called from invalid context in %[2]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
			{
				title: compile("BUG: using ([a-z_]+)\\(\\) in preemptible"),
				fmt:   "BUG: using %[1]v() in preemptible code in %[2]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"dump_stack", "preemption", "preempt", "debug_",
						"processor_id", "this_cpu"},
				},
			},
			{
				title: compile("BUG: workqueue leaked lock or atomic"),
				report: compile("BUG: workqueue leaked lock or atomic(?:.*\\n)+?" +
					".*last function: ([a-zA-Z0-9_]+)\\n"),
				fmt:          "BUG: workqueue leaked lock or atomic in %[1]v",
				noStackTrace: true,
			},
			{
				title: compile("BUG: memory leak"),
				fmt:   "memory leak in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						compile("backtrace:"),
						parseStackTrace,
					},
					skip: []string{"kmemleak", "mmap", "kmem", "slab", "alloc", "create_object",
						"idr_get", "list_lru_init", "kasprintf", "kvasprintf",
						"pcpu_create", "strdup", "strndup", "memdup"},
				},
			},
			{
				title: compile("BUG: .*stack guard page was hit at"),
				fmt:   "BUG: stack guard page was hit in %[1]v",
				alt:   []string{"stack-overflow in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
						linuxCallTrace,
						parseStackTrace,
					},
					extractor: linuxStallFrameExtractor,
				},
			},
			{
				title: compile("BUG: Invalid wait context"),
				// Somehow amd64 and arm/arm64 report this bug completely differently.
				// This is arm/arm64 format, but we match amd64 title to not duplicate bug reports.
				fmt: "WARNING: locking bug in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"lock_sock", "release_sock"},
				},
			},
			{
				title:     compile(`BUG:[[:space:]]*(?:\n|$)`),
				fmt:       "BUG: corrupted",
				corrupted: true,
			},
		},
		[]*regexp.Regexp{
			// CONFIG_DEBUG_OBJECTS output.
			compile("ODEBUG:"),
			// Android prints this sometimes during boot.
			compile("Boot_DEBUG:"),
			compile("xlog_status:"),
			// Android ART debug output.
			compile("DEBUG:"),
			// pkg/host output in debug mode.
			compile("BUG: no syscalls can create resource"),
		},
	},
	{
		[]byte("WARNING:"),
		[]oopsFormat{
			{
				title: compile("WARNING: .*lib/debugobjects\\.c.* (?:debug_print|debug_check)"),
				fmt:   "WARNING: ODEBUG bug in %[1]v",
				// Skip all users of ODEBUG as well.
				stack: warningStackFmt("debug_", "rcu", "hrtimer_", "timer_",
					"work_", "percpu_", "vunmap",
					"vfree", "__free_", "debug_check", "kobject_"),
			},
			{
				title: compile("WARNING: .*mm/usercopy\\.c.* usercopy_warn"),
				fmt:   "WARNING: bad usercopy in %[1]v",
				stack: warningStackFmt("usercopy", "__check"),
			},
			{
				title: compile("WARNING: .*lib/kobject\\.c.* kobject_"),
				fmt:   "WARNING: kobject bug in %[1]v",
				stack: warningStackFmt("kobject_"),
			},
			{
				title: compile("WARNING: .*fs/proc/generic\\.c.* proc_register"),
				fmt:   "WARNING: proc registration bug in %[1]v",
				stack: warningStackFmt("proc_"),
			},
			{
				title: compile("WARNING: .*lib/refcount\\.c.* refcount_"),
				fmt:   "WARNING: refcount bug in %[1]v",
				stack: warningStackFmt("refcount", "kobject_"),
			},
			{
				title: compile("WARNING: .*kernel/locking/lockdep\\.c.*lock_"),
				fmt:   "WARNING: locking bug in %[1]v",
				stack: warningStackFmt("lock_sock", "release_sock"),
			},
			{
				title:  compile("WARNING: .*still has locks held!"),
				report: compile("WARNING: .*still has locks held!(?:.*\\n)+?.*at: {{FUNC}}"),
				fmt:    "WARNING: still has locks held in %[1]v",
			},
			{
				title: compile("WARNING: Nested lock was not taken"),
				fmt:   "WARNING: nested lock was not taken in %[1]v",
				stack: warningStackFmt(),
			},
			{
				title:        compile("WARNING: lock held when returning to user space"),
				report:       compile("WARNING: lock held when returning to user space(?:.*\\n)+?.*leaving the kernel with locks still held(?:.*\\n)+?.*at: (?:{{PC}} +)?{{FUNC}}"),
				fmt:          "WARNING: lock held when returning to user space in %[1]v",
				noStackTrace: true,
			},
			{
				title: compile("WARNING: .*mm/.*\\.c.* k?.?malloc"),
				fmt:   "WARNING: kmalloc bug in %[1]v",
				stack: warningStackFmt("kmalloc", "krealloc", "slab", "kmem"),
			},
			{
				title: compile("WARNING: .*mm/vmalloc.c.*__vmalloc_node"),
				fmt:   "WARNING: zero-size vmalloc in %[1]v",
				stack: warningStackFmt(),
			},
			{
				title: compile("WARNING: .* usb_submit_urb"),
				fmt:   "WARNING in %[1]v/usb_submit_urb",
				stack: warningStackFmt("usb_submit_urb", "usb_start_wait_urb", "usb_bulk_msg", "usb_interrupt_msg", "usb_control_msg"),
			},
			{
				title: compile("WARNING: .* at {{SRC}} {{FUNC}}"),
				fmt:   "WARNING in %[3]v",
				stack: warningStackFmt(),
			},
			{
				title: compile("WARNING: {{SRC}} at {{FUNC}}"),
				fmt:   "WARNING in %[3]v",
				stack: warningStackFmt(),
			},
			{
				title:  compile("WARNING: possible circular locking dependency detected"),
				report: compile("WARNING: possible circular locking dependency detected(?:.*\\n)+?.*is trying to acquire lock"),
				fmt:    "possible deadlock in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						compile("at: (?:{{PC}} +)?{{FUNC}}"),
						compile("at: (?:{{PC}} +)?{{FUNC}}"),
						parseStackTrace,
					},
					// These workqueue functions take locks associated with work items.
					// All deadlocks observed in these functions are
					// work-item-subsystem-related.
					skip: []string{"process_one_work", "flush_workqueue",
						"drain_workqueue", "destroy_workqueue"},
				},
			},
			{
				title:  compile("WARNING: possible irq lock inversion dependency detected"),
				report: compile("WARNING: possible irq lock inversion dependency detected(?:.*\\n)+?.*just changed the state of lock(?:.*\\n)+?.*at: (?:{{PC}} +)?{{FUNC}}"),
				fmt:    "possible deadlock in %[1]v",
			},
			{
				title: compile("WARNING: .*-safe -> .*-unsafe lock order detected"),
				fmt:   "possible deadlock in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						compile("which became (?:.*) at:"),
						parseStackTrace,
					},
				},
			},
			{
				title:  compile("WARNING: possible recursive locking detected"),
				report: compile("WARNING: possible recursive locking detected(?:.*\\n)+?.*is trying to acquire lock(?:.*\\n)+?.*at: (?:{{PC}} +)?{{FUNC}}"),
				fmt:    "possible deadlock in %[1]v",
			},
			{
				title:  compile("WARNING: inconsistent lock state"),
				report: compile("WARNING: inconsistent lock state(?:.*\\n)+?.*takes(?:.*\\n)+?.*at: (?:{{PC}} +)?{{FUNC}}"),
				fmt:    "inconsistent lock state in %[2]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
			{
				title:  compile("WARNING: suspicious RCU usage"),
				report: compile("WARNING: suspicious RCU usage(?:.*\n)+?.*?{{SRC}}"),
				fmt:    "WARNING: suspicious RCU usage in %[2]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"rcu", "kmem", "slab"},
				},
			},
			{
				title:        compile("WARNING: kernel stack regs at [0-9a-f]+ in [^ ]* has bad '([^']+)' value"),
				fmt:          "WARNING: kernel stack regs has bad '%[1]v' value",
				noStackTrace: true,
			},
			{
				title:        compile("WARNING: kernel stack frame pointer at [0-9a-f]+ in [^ ]* has bad value"),
				fmt:          "WARNING: kernel stack frame pointer has bad value",
				noStackTrace: true,
			},
			{
				title: compile("WARNING: bad unlock balance detected!"),
				fmt:   "WARNING: bad unlock balance in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						compile("{{PC}} +{{FUNC}}"),
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
			{
				title:  compile("WARNING: held lock freed!"),
				report: compile("WARNING: held lock freed!(?:.*\\n)+?.*at:(?: {{PC}})? +{{FUNC}}"),
				fmt:    "WARNING: held lock freed in %[1]v",
			},
			{
				title:        compile("WARNING: kernel stack regs .* has bad 'bp' value"),
				fmt:          "WARNING: kernel stack regs has bad value",
				noStackTrace: true,
			},
			{
				title:        compile("WARNING: kernel stack frame pointer .* has bad value"),
				fmt:          "WARNING: kernel stack regs has bad value",
				noStackTrace: true,
			},
			{
				title:     compile(`WARNING:[[:space:]]*(?:\n|$)`),
				fmt:       "WARNING: corrupted",
				corrupted: true,
			},
		},
		[]*regexp.Regexp{
			compile("WARNING: /etc/ssh/moduli does not exist, using fixed modulus"), // printed by sshd
			compile("WARNING: workqueue cpumask: online intersect > possible intersect"),
			compile("WARNING: [Tt]he mand mount option"),
			compile("WARNING: Unsupported flag value\\(s\\) of 0x%x in DT_FLAGS_1"), // printed when glibc is dumped
			compile("WARNING: Unprivileged eBPF is enabled with eIBRS"),
			compile(`WARNING: fbcon: Driver '(.*)' missed to adjust virtual screen size (\((?:\d+)x(?:\d+) vs\. (?:\d+)x(?:\d+)\))`),
			compile(`WARNING: See https.* for mitigation options.`),
			compile(`WARNING: kernel not compiled with CPU_SRSO`),
			compile(`EXT4-[Ff][Ss](?: \(.*\))?:`), // printed in __ext4_msg
			compile(`(?i)warning: .* uses (deprecated v2 capabilities|wireless extensions)`),
			compile(`XFS \(\w+\): WARNING`),
		},
	},
	{
		[]byte("INFO:"),
		[]oopsFormat{
			{
				title:  compile("INFO: possible circular locking dependency detected"),
				report: compile("INFO: possible circular locking dependency detected \\](?:.*\\n)+?.*is trying to acquire lock(?:.*\\n)+?.*at: {{PC}} +{{FUNC}}"),
				fmt:    "possible deadlock in %[1]v",
			},
			{
				title:  compile("INFO: possible irq lock inversion dependency detected"),
				report: compile("INFO: possible irq lock inversion dependency detected \\](?:.*\\n)+?.*just changed the state of lock(?:.*\\n)+?.*at: {{PC}} +{{FUNC}}"),
				fmt:    "possible deadlock in %[1]v",
			},
			{
				title:  compile("INFO: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected"),
				report: compile("INFO: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected \\](?:.*\\n)+?.*is trying to acquire(?:.*\\n)+?.*at: {{PC}} +{{FUNC}}"),
				fmt:    "possible deadlock in %[1]v",
			},
			{
				title:  compile("INFO: possible recursive locking detected"),
				report: compile("INFO: possible recursive locking detected \\](?:.*\\n)+?.*is trying to acquire lock(?:.*\\n)+?.*at: {{PC}} +{{FUNC}}"),
				fmt:    "possible deadlock in %[1]v",
			},
			{
				title:  compile("INFO: inconsistent lock state"),
				report: compile("INFO: inconsistent lock state \\](?:.*\\n)+?.*takes(?:.*\\n)+?.*at: {{PC}} +{{FUNC}}"),
				fmt:    "inconsistent lock state in %[1]v",
			},
			{
				title: compile("INFO: rcu_(?:preempt|sched|bh) (?:self-)?detected(?: expedited)? stall"),
				fmt:   "INFO: rcu detected stall in %[1]v",
				alt:   []string{"stall in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						compile("apic_timer_interrupt"),
						linuxRipFrame,
						parseStackTrace,
					},
					parts2: []*regexp.Regexp{
						compile("(?:apic_timer_interrupt|Exception stack|el1h_64_irq)"),
						parseStackTrace,
					},
					skip:      []string{"apic_timer_interrupt", "rcu"},
					extractor: linuxStallFrameExtractor,
				},
			},
			{
				title: compile("INFO: trying to register non-static key"),
				fmt:   "INFO: trying to register non-static key in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"stack", "lock", "IRQ"},
				},
			},
			{
				title:  compile("INFO: suspicious RCU usage"),
				report: compile("INFO: suspicious RCU usage(?:.*\n)+?.*?{{SRC}}"),
				fmt:    "INFO: suspicious RCU usage in %[2]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"rcu", "kmem", "slab"},
				},
			},
			{
				title: compile("INFO: task .* blocked for more than [0-9]+ seconds"),
				fmt:   "INFO: task hung in %[1]v",
				alt:   []string{"hang in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					extractor: linuxHangTaskFrameExtractor,
				},
			},
			{
				title: compile("INFO: task .* can't die for more than .* seconds"),
				fmt:   "INFO: task can't die in %[1]v",
				alt:   []string{"hang in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"schedule"},
				},
			},
			{
				// This gets captured for corrupted old-style KASAN reports.
				title:     compile("INFO: (Freed|Allocated) in (.*)"),
				fmt:       "INFO: %[1]v in %[2]v",
				corrupted: true,
			},
			{
				title:     compile(`INFO:[[:space:]]*(?:\n|$)`),
				fmt:       "INFO: corrupted",
				corrupted: true,
			},
		},
		[]*regexp.Regexp{
			compile("INFO: lockdep is turned off"),
			compile("INFO: Stall ended before state dump start"),
			compile("INFO: NMI handler"),
			compile("INFO: recovery required on readonly filesystem"),
			compile("(handler|interrupt).*took too long"),
			compile("INFO: sys_.* is not present in /proc/kallsyms"), // pkg/host output in debug mode
			compile("INFO: no syscalls can create resource"),         // pkg/host output in debug mode
			compile("rmt_storage:INFO:"),                             // Android prints this.
			compile("_INFO:"),                                        // To filter out "INVALID BTF_INFO:NUM".
		},
	},
	{
		[]byte("Unable to handle kernel"),
		[]oopsFormat{
			{
				title: compile("Unable to handle kernel (paging request|NULL pointer dereference|access to user memory)"),
				fmt:   "BUG: unable to handle kernel %[1]v in %[2]v",
				alt:   []string{"bad-access in %[2]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("general protection fault"),
		[]oopsFormat{
			{
				title: compile("general protection fault.*:"),
				fmt:   "general protection fault in %[1]v",
				alt:   []string{"bad-access in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
		},
		[]*regexp.Regexp{
			compile(`general protection fault .* error:\d+ in `),
		},
	},
	{
		[]byte("stack segment: "),
		[]oopsFormat{
			{
				title: compile("stack segment: "),
				fmt:   "stack segment fault in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("Kernel panic"),
		[]oopsFormat{
			// Note: for stack corruption reports kernel may fail
			// to print function symbol name and/or unwind stack.
			{
				title:        compile("Kernel panic - not syncing: stack-protector:"),
				report:       compile("Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: {{FUNC}}"),
				fmt:          "kernel panic: stack is corrupted in %[1]v",
				noStackTrace: true,
			},
			{
				title:  compile("Kernel panic - not syncing: stack-protector:"),
				report: compile("Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: [a-f0-9]+"),
				fmt:    "kernel panic: stack is corrupted in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"stack_chk"},
				},
			},
			{
				title:  compile("Kernel panic - not syncing: corrupted stack end"),
				report: compile("Kernel panic - not syncing: corrupted stack end detected inside scheduler"),
				fmt:    "kernel panic: corrupted stack end in %[1]v",
				alt:    []string{"stack-overflow in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip:      []string{"schedule", "retint_kernel"},
					extractor: linuxStallFrameExtractor,
				},
			},
			{
				title: compile("Kernel panic - not syncing: kernel stack overflow"),
				fmt:   "kernel stack overflow in %[1]v",
				alt:   []string{"stack-overflow in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip:      []string{"bad_stack"},
					extractor: linuxStallFrameExtractor,
				},
			},
			{
				title: compile("Kernel panic - not syncing: Attempted to kill init!"),
				fmt:   "kernel panic: Attempted to kill init!",
			},
			{
				title: compile("Kernel panic - not syncing: Couldn't open N_TTY ldisc for [^ ]+ --- error -[0-9]+"),
				fmt:   "kernel panic: Couldn't open N_TTY ldisc",
			},
			{
				// 'kernel panic: Fatal exception' is usually printed after BUG,
				// so if we captured it as a report description, that means the
				// report got truncated and we missed the actual BUG header.
				title:     compile("Kernel panic - not syncing: Fatal exception"),
				fmt:       "kernel panic: Fatal exception",
				corrupted: true,
			},
			{
				// Same, but for WARNINGs and KASAN reports.
				title:     compile("Kernel panic - not syncing: panic_on_warn set"),
				fmt:       "kernel panic: panic_on_warn set",
				corrupted: true,
			},
			{
				// Same, but for task hung reports.
				title:     compile("Kernel panic - not syncing: hung_task: blocked tasks"),
				fmt:       "kernel panic: hung_task: blocked tasks",
				corrupted: true,
			},
			{
				title: compile("Kernel panic - not syncing: (.*)"),
				fmt:   "kernel panic: %[1]v",
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("PANIC: double fault"),
		[]oopsFormat{
			{
				title: compile("PANIC: double fault"),
				fmt:   "PANIC: double fault in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
					},
				},
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("rust_kernel: panicked"),
		[]oopsFormat{
			{
				title:  compile("rust_kernel: panicked"),
				report: compile("rust_kernel: panicked at [^\n]*?\n(.+?)\n"),
				fmt:    "%[1]v in %[2]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{
						regexp.QuoteMeta(`__rustc::rust_begin_unwind`),
					},
				},
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("kernel BUG"),
		[]oopsFormat{
			{
				title: compile("kernel BUG at mm/usercopy.c"),
				fmt:   "BUG: bad usercopy in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"usercopy", "__check"},
				},
			},
			{
				title: compile("kernel BUG at lib/list_debug.c"),
				fmt:   "BUG: corrupted list in %[1]v",
				alt:   []string{"bad-access in %[1]v"}, // also sometimes due to memory corruption/race
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
			{
				title: compile("kernel BUG at (.*)"),
				fmt:   "kernel BUG in %[2]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
						linuxCallTrace,
						parseStackTrace,
					},
					// Lots of skb wrappers contain BUG_ON, but the bug is almost always in the caller.
					skip: []string{"^skb_"},
				},
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("Kernel BUG"),
		[]oopsFormat{
			{
				title: compile("Kernel BUG (.*)"),
				fmt:   "kernel BUG %[1]v",
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("BUG kmalloc-"),
		[]oopsFormat{
			{
				title: compile("BUG kmalloc-.*: Object already free"),
				fmt:   "BUG: Object already free",
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("divide error:"),
		[]oopsFormat{
			{
				title: compile("divide error: "),
				fmt:   "divide error in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
					},
				},
			},
		},
		[]*regexp.Regexp{},
	},
	{
		// A misspelling of the above introduced in 9d06c4027f21 ("x86/entry: Convert Divide Error to IDTENTRY").
		[]byte("divide_error:"),
		[]oopsFormat{
			{
				title: compile("divide_error: "),
				fmt:   "divide error in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
					},
				},
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("invalid opcode:"),
		[]oopsFormat{
			{
				title: compile("invalid opcode: "),
				fmt:   "invalid opcode in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
					},
				},
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("UBSAN:"),
		[]oopsFormat{
			{
				title:  compile("UBSAN:"),
				report: compile("UBSAN: Undefined behaviour in"),
				fmt:    "UBSAN: undefined-behaviour in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"ubsan", "overflow"},
				},
			},
			{
				title: compile("UBSAN: array-index-out-of-bounds in"),
				fmt:   "UBSAN: array-index-out-of-bounds in %[1]v",
				alt:   []string{"bad-access in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"ubsan", "overflow"},
				},
			},
			{
				title:  compile("UBSAN:"),
				report: compile("UBSAN: (.*?) in"),
				fmt:    "UBSAN: %[1]v in %[2]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxCallTrace,
						parseStackTrace,
					},
					skip: []string{"ubsan", "overflow"},
				},
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("Booting the kernel."),
		[]oopsFormat{
			{
				title:        compile("^Booting the kernel"),
				fmt:          "unexpected kernel reboot",
				noStackTrace: true,
			},
		},
		[]*regexp.Regexp{
			// These may appear on the same line when the fuzzer reads from the console the existing
			// boot message and then pass it as mount option, kernel then prints it back
			// as an invalid mount option and we detect false reboot.
			compile("Parsing ELF|Decompressing Linux|Unknown parameter '"),
		},
	},
	{
		[]byte("unregister_netdevice: waiting for"),
		[]oopsFormat{
			{
				title:        compile("unregister_netdevice: waiting for (?:.*) to become free"),
				fmt:          "unregister_netdevice: waiting for DEV to become free",
				noStackTrace: true,
			},
		},
		[]*regexp.Regexp{},
	},
	{
		// Custom vfs error printed by older versions of the kernel, see #3621.
		[]byte("VFS: Close: file count is 0"),
		[]oopsFormat{
			{
				title:        compile("VFS: Close: file count is 0"),
				fmt:          "VFS: Close: file count is zero (use-after-free)",
				noStackTrace: true,
			},
		},
		[]*regexp.Regexp{},
	},
	{
		// Custom vfs error printed by older versions of the kernel, see #3621.
		[]byte("VFS: Busy inodes after unmount"),
		[]oopsFormat{
			{
				title:        compile("VFS: Busy inodes after unmount"),
				fmt:          "VFS: Busy inodes after unmount (use-after-free)",
				noStackTrace: true,
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("Internal error:"),
		[]oopsFormat{
			{
				title: compile("Internal error:"),
				fmt:   "Internal error in %[1]v",
				// arm64 shows some crashes as "Internal error: synchronous external abort",
				// while arm shows the same crash as "Unable to handle kernel paging request",
				// so we need to merge them.
				alt: []string{"bad-access in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("Unhandled fault:"),
		[]oopsFormat{
			{
				title: compile("Unhandled fault:"),
				fmt:   "Unhandled fault in %[1]v",
				// x86_64 shows NULL derefs as "general protection fault",
				// while arm shows the same crash as "Unhandled fault: page domain fault".
				alt: []string{"bad-access in %[1]v"},
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("Alignment trap:"),
		[]oopsFormat{
			{
				title: compile("Alignment trap:"),
				fmt:   "Alignment trap in %[1]v",
				stack: &stackFmt{
					parts: []*regexp.Regexp{
						linuxRipFrame,
						linuxCallTrace,
						parseStackTrace,
					},
				},
			},
		},
		[]*regexp.Regexp{},
	},
	{
		[]byte("trusty: panic"),
		[]oopsFormat{
			{
				title:        compile("trusty: panic.* ASSERT FAILED"),
				report:       compile("trusty: panic \\(.*?\\):(?: DEBUG)? ASSERT FAILED at \\(.*?\\): (.+)"),
				fmt:          "trusty: ASSERT FAILED: %[1]v",
				noStackTrace: true,
			},
			{
				title:     compile("trusty: panic.* ASSERT FAILED.*: *(.*)"),
				fmt:       "trusty: ASSERT FAILED: %[1]v",
				corrupted: true,
			},
			{
				title:        compile("trusty: panic"),
				report:       compile("trusty: panic \\(.*?\\): (.+)"),
				fmt:          "trusty: panic: %[1]v",
				noStackTrace: true,
			},
		},
		[]*regexp.Regexp{},
	},
	&groupGoRuntimeErrors,
}, commonOopses...)