pkg/report: handle cases when whole stack is questionable

If the report is identified as corrupted because there are no frames at all,
try to re-extract using questionable frames.
This is a bit risky and may produce lots of one-off corrupted reports
at random locations. But we won't know until we deploy this...

Fixes #1216

6 files changed, 447 insertions, 42 deletions

diff --git a/pkg/report/linux.go b/pkg/report/linux.go
index 4821f78eb..31b6be136 100644
--- a/pkg/report/linux.go
+++ b/pkg/report/linux.go
@@ -23,7 +23,6 @@ type linux struct {
 	vmlinux               string
 	symbols               map[string][]symbolizer.Symbol
 	consoleOutputRe       *regexp.Regexp
-	questionableRes       []*regexp.Regexp
 	taskContext           *regexp.Regexp
 	cpuContext            *regexp.Regexp
 	guiltyFileBlacklist   []*regexp.Regexp
@@ -49,10 +48,6 @@ func ctorLinux(cfg *config) (Reporter, []string, error) {
 		symbols: symbols,
 	}
 	ctx.consoleOutputRe = regexp.MustCompile(`^(?:\*\* [0-9]+ printk messages dropped \*\* )?(?:.* login: )?(?:\<[0-9]+\>)?\[ *[0-9]+\.[0-9]+\](\[ *(?:C|T)[0-9]+\])? `)
-	ctx.questionableRes = []*regexp.Regexp{
-		regexp.MustCompile(`(\[\<[0-9a-f]+\>\])? \? +[a-zA-Z0-9_.]+\+0x[0-9a-f]+/[0-9a-f]+`),
-		regexp.MustCompile(`\(unreliable\)`), // powerpc
-	}
 	ctx.taskContext = regexp.MustCompile(`\[ *T[0-9]+\]`)
 	ctx.cpuContext = regexp.MustCompile(`\[ *C[0-9]+\]`)
 	ctx.eoi = []byte("<EOI>")
@@ -124,6 +119,8 @@ func ctorLinux(cfg *config) (Reporter, []string, error) {
 	return ctx, suppressions, nil
 }
 
+const contextConsole = "console"
+
 func (ctx *linux) ContainsCrash(output []byte) bool {
 	return containsCrash(output, linuxOopses, ctx.ignores)
 }
@@ -133,35 +130,46 @@ func (ctx *linux) Parse(output []byte) *Report {
 	if oops == nil {
 		return nil
 	}
-	rep := &Report{
-		Output:   output,
-		StartPos: startPos,
-	}
-	endPos, reportEnd, report, prefix := ctx.findReport(output, oops, startPos, context)
-	rep.EndPos = endPos
-	title, corrupted, format := extractDescription(report[:reportEnd], oops, linuxStackParams)
-	if title == "" {
-		prefix = nil
-		report = output[rep.StartPos:rep.EndPos]
-		title, corrupted, format = extractDescription(report, oops, linuxStackParams)
+	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, format := extractDescription(report[:reportEnd], oops, linuxStackParams)
 		if title == "" {
-			panic(fmt.Sprintf("non matching oops for %q context=%q in:\n%s\n",
-				oops.header, context, report))
+			prefix = nil
+			report = output[rep.StartPos:rep.EndPos]
+			title, corrupted, 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.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...)
+		if !rep.Corrupted {
+			rep.Corrupted, rep.CorruptedReason = ctx.isCorrupted(title, report, format)
+		}
+		if rep.CorruptedReason == corruptedNoFrames && context != contextConsole && !questionable {
+			// 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.
+			continue
+		}
+		return rep
 	}
-	rep.Title = title
-	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...)
-	if !rep.Corrupted {
-		rep.Corrupted, rep.CorruptedReason = ctx.isCorrupted(title, report, format)
-	}
-	return rep
 }
 
 func (ctx *linux) findFirstOops(output []byte) (oops *oops, startPos int, context string) {
@@ -187,7 +195,7 @@ func (ctx *linux) findFirstOops(output []byte) (oops *oops, startPos int, contex
 
 // Yes, it is complex, but all state and logic are tightly coupled. It's unclear how to simplify it.
 // nolint: gocyclo
-func (ctx *linux) findReport(output []byte, oops *oops, startPos int, context string) (
+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.
@@ -208,7 +216,7 @@ func (ctx *linux) findReport(output []byte, oops *oops, startPos int, context st
 		}
 		line := output[pos:next]
 		context1 := ctx.extractContext(line)
-		stripped, questionable := ctx.stripLinePrefix(line, context1)
+		stripped, questionable := ctx.stripLinePrefix(line, context1, useQuestionable)
 		if pos < startPos {
 			if context1 == context && len(stripped) != 0 && !questionable {
 				prefix = append(prefix, append([]byte{}, stripped...))
@@ -274,27 +282,33 @@ func (ctx *linux) findReport(output []byte, oops *oops, startPos int, context st
 		}
 		report = append(report, stripped...)
 		report = append(report, '\n')
-		if secondReportPos == 0 || context != "" && context != "console" {
+		if secondReportPos == 0 || context != "" && context != contextConsole {
 			reportEnd = len(report)
 		}
 	}
 	return
 }
 
-func (ctx *linux) stripLinePrefix(line []byte, context string) ([]byte, bool) {
+func (ctx *linux) stripLinePrefix(line []byte, context string, useQuestionable bool) ([]byte, bool) {
 	if last := len(line) - 1; last >= 0 && line[last] == '\r' {
 		line = line[:last]
 	}
 	if context == "" {
 		return line, false
 	}
-	start := bytes.Index(line, []byte("] ")) + 2
-	for _, re := range ctx.questionableRes {
-		if re.Match(line) && !bytes.Contains(line, ctx.eoi) {
-			return line[start:], true
+	start := bytes.Index(line, []byte("] "))
+	line = line[start+2:]
+	if !bytes.Contains(line, ctx.eoi) {
+		// x86_64 prefix.
+		if bytes.HasPrefix(line, []byte(" ? ")) {
+			return line[2:], !useQuestionable
+		}
+		// powerpc suffix.
+		if bytes.HasSuffix(line, []byte(" (unreliable)")) {
+			return line[:len(line)-13], !useQuestionable
 		}
 	}
-	return line[start:], false
+	return line, false
 }
 
 func (ctx *linux) extractContext(line []byte) string {
@@ -303,7 +317,7 @@ func (ctx *linux) extractContext(line []byte) string {
 		return ""
 	}
 	if match[2] == -1 {
-		return "console"
+		return contextConsole
 	}
 	return string(line[match[2]:match[3]])
 }
diff --git a/pkg/report/report.go b/pkg/report/report.go
index c9832c9af..4d16edd51 100644
--- a/pkg/report/report.go
+++ b/pkg/report/report.go
@@ -123,6 +123,7 @@ const (
 	unexpectedKernelReboot = "unexpected kernel reboot"
 	memoryLeakPrefix       = "memory leak in "
 	dataRacePrefix         = "KCSAN: data-race"
+	corruptedNoFrames      = "extracted no frames"
 )
 
 var ctors = map[string]fn{
@@ -511,7 +512,7 @@ nextPart:
 		}
 	}
 	if len(frames) == 0 {
-		return "", "extracted no frames"
+		return "", corruptedNoFrames
 	}
 	return extractor(frames)
 }
diff --git a/pkg/report/testdata/linux/report/479 b/pkg/report/testdata/linux/report/479
new file mode 100644
index 000000000..6c6166647
--- /dev/null
+++ b/pkg/report/testdata/linux/report/479
@@ -0,0 +1,250 @@
+TITLE: BUG: unable to handle kernel paging request in nf_tables_newflowtable
+
+[  490.564553][T16898] BUG: unable to handle page fault for address: 0000000000ffff88
+[  490.572415][T16898] #PF: supervisor read access in kernel mode
+[  490.578422][T16898] #PF: error_code(0x0000) - not-present page
+[  490.584378][T16898] PGD 862e4067 P4D 862e4067 PUD 9961c067 PMD 0 
+[  490.590606][T16898] Oops: 0000 [#1] PREEMPT SMP
+[  490.595264][T16898] CPU: 1 PID: 16898 Comm: syz-executor.3 Not tainted 5.6.0-rc1-syzkaller #0
+[  490.604044][T16898] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
+[  490.616101][T16898] RIP: 0010:__list_del_entry_valid+0x59/0x8e
+[  490.622083][T16898] Code: 00 00 00 00 ad de 49 39 c4 0f 84 92 00 00 00 48 b8 22 01 00 00 00 00 ad de 49 39 c5 0f 84 b8 00 00 00 4c 89 ef e8 77 4c 00 ff <4d> 8b 6d 00 49 39 ed 0f 85 8f 00 00 00 49 8d 7c 24 08 e8 60 4c 00
+[  490.641675][T16898] RSP: 0018:ffffc9000902f7d0 EFLAGS: 00010202
+[  490.647729][T16898] RAX: 0000000000000afb RBX: ffff888120ab9e00 RCX: ffffffff86d9d6b0
+[  490.655685][T16898] RDX: 0000000000000000 RSI: ffff88808aa81a01 RDI: 0000000000ffff88
+[  490.663645][T16898] RBP: ffff88808aa81a05 R08: 0000000000000000 R09: 0000000000ffff88
+[  490.671622][T16898] R10: 0000888120ab9e48 R11: 0000000000ffff8f R12: 80ae4b8ef8ffff88
+[  490.679590][T16898] R13: 0000000000ffff88 R14: ffff88808aa81a00 R15: ffff8880ae4b8100
+[  490.687557][T16898] FS:  00007f0364420700(0000) GS:ffff88812c100000(0000) knlGS:0000000000000000
+[  490.696473][T16898] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+[  490.703106][T16898] CR2: 0000000000ffff88 CR3: 000000008b30d000 CR4: 00000000001406e0
+[  490.711077][T16898] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
+[  490.719062][T16898] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
+[  490.727070][T16898] Call Trace:
+[  490.730505][T16898]  ? __list_add+0x40/0xd0
+[  490.734877][T16898]  ? nf_tables_newflowtable+0xcee/0xf00
+[  490.740427][T16898]  ? nft_trans_alloc_gfp+0xc0/0xc0
+[  490.745550][T16898]  ? nfnetlink_rcv_batch+0x528/0xbd0
+[  490.750871][T16898]  ? __nla_validate_parse+0xa8/0x11d0
+[  490.756239][T16898]  ? security_capable+0x8a/0xa0
+[  490.761195][T16898]  ? ns_capable_common+0xad/0xc0
+[  490.766142][T16898]  ? __nla_parse+0x4b/0x60
+[  490.770548][T16898]  ? nfnetlink_rcv+0x269/0x290
+[  490.775300][T16898]  ? netlink_unicast+0x390/0x4c0
+[  490.780291][T16898]  ? netlink_sendmsg+0x4cf/0x8a0
+[  490.785216][T16898]  ? netlink_unicast+0x4c0/0x4c0
+[  490.790131][T16898]  ? sock_sendmsg+0x98/0xc0
+[  490.794634][T16898]  ? ____sys_sendmsg+0x493/0x4c0
+[  490.799730][T16898]  ? ___sys_sendmsg+0xb5/0x100
+[  490.804505][T16898]  ? __rcu_read_unlock+0x66/0x2f0
+[  490.809583][T16898]  ? __fget_files+0xa2/0x1c0
+[  490.814237][T16898]  ? __fget_light+0xc0/0x1a0
+[  490.818811][T16898]  ? __fdget+0x29/0x30
+[  490.822862][T16898]  ? sockfd_lookup_light+0xa5/0x100
+[  490.828065][T16898]  ? __sys_sendmsg+0x9b/0x150
+[  490.832740][T16898]  ? __x64_sys_sendmsg+0x4c/0x60
+[  490.837671][T16898]  ? do_syscall_64+0xc7/0x390
+[  490.842344][T16898]  ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
+[  490.848485][T16898] Modules linked in:
+[  490.852420][T16898] CR2: 0000000000ffff88
+[  490.856659][T16896] BUG: unable to handle page fault for address: 0000000100ffffc9
+[  490.864378][T16896] #PF: supervisor read access in kernel mode
+[  490.870346][T16896] #PF: error_code(0x0000) - not-present page
+[  490.876346][T16896] PGD 0 P4D 0 
+[  490.879714][T16896] Oops: 0000 [#2] PREEMPT SMP
+[  490.884377][T16896] CPU: 0 PID: 16896 Comm: sh Tainted: G      D           5.6.0-rc1-syzkaller #0
+[  490.893399][T16896] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
+[  490.903531][T16896] RIP: 0010:__list_del_entry_valid+0x59/0x8e
+[  490.909499][T16896] Code: 00 00 00 00 ad de 49 39 c4 0f 84 92 00 00 00 48 b8 22 01 00 00 00 00 ad de 49 39 c5 0f 84 b8 00 00 00 4c 89 ef e8 77 4c 00 ff <4d> 8b 6d 00 49 39 ed 0f 85 8f 00 00 00 49 8d 7c 24 08 e8 60 4c 00
+[  490.929309][T16896] RSP: 0018:ffffc90008fffb70 EFLAGS: 00010006
+[  490.935750][T16896] RAX: 000000000000036a RBX: 0000000000000000 RCX: ffffffff86d9d6b0
+[  490.943714][T16896] RDX: 0000000000000000 RSI: ffffc90008fffbd9 RDI: 0000000100ffffc9
+[  490.951762][T16896] RBP: ffffc90008fffbdd R08: 0000000000000000 R09: 0000000100ffffc9
+[  490.959728][T16896] R10: 0000ffffffffffff R11: 0000000100ffffd0 R12: 0008fffbd8ffffc9
+[  490.968083][T16896] R13: 0000000100ffffc9 R14: ffffc90008fffbd8 R15: ffffea00043d5c80
+[  490.976052][T16896] FS:  0000000000000000(0000) GS:ffff88812c000000(0000) knlGS:0000000000000000
+[  490.985008][T16896] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+[  490.991683][T16896] CR2: 0000000100ffffc9 CR3: 0000000005a23000 CR4: 00000000001406f0
+[  490.999644][T16896] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
+[  491.007609][T16896] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
+[  491.015569][T16896] Call Trace:
+[  491.018893][T16896]  ? release_pages+0x7a3/0x9b0
+[  491.023651][T16896]  ? free_pages_and_swap_cache+0x231/0x2a0
+[  491.029443][T16896]  ? tlb_flush_mmu+0x76/0x390
+[  491.034566][T16896]  ? tlb_finish_mmu+0x7f/0x230
+[  491.039518][T16896]  ? exit_mmap+0x15e/0x2f0
+[  491.044021][T16896]  ? mmput+0xe2/0x260
+[  491.048012][T16896]  ? do_exit+0x640/0x1880
+[  491.052543][T16896]  ? recalc_sigpending+0x4f/0xe0
+[  491.058572][T16896]  ? do_sigaltstack.constprop.0+0x2b5/0x390
+[  491.064513][T16896]  ? _copy_from_user+0x93/0xf0
+[  491.069330][T16896]  ? do_group_exit+0xae/0x1a0
+[  491.074018][T16896]  ? __x64_sys_exit_group+0x2b/0x30
+[  491.079224][T16896]  ? do_syscall_64+0xc7/0x390
+[  491.083977][T16896]  ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
+[  491.090448][T16896] Modules linked in:
+[  491.094324][T16896] CR2: 0000000100ffffc9
+[  491.098573][T16896] ---[ end trace a5ad8ea8946e7e64 ]---
+[  491.098603][    C1] BUG: unable to handle page fault for address: 0000000000ffff88
+[  491.104175][T16896] RIP: 0010:__list_del_entry_valid+0x59/0x8e
+[  491.111928][    C1] #PF: supervisor read access in kernel mode
+[  491.111935][    C1] #PF: error_code(0x0000) - not-present page
+[  491.111941][    C1] PGD 862e4067 P4D 862e4067 PUD 9961c067 PMD 0 
+[  491.111963][    C1] Oops: 0000 [#3] PREEMPT SMP
+[  491.111978][    C1] CPU: 1 PID: 16898 Comm: syz-executor.3 Tainted: G      D           5.6.0-rc1-syzkaller #0
+[  491.111996][    C1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
+[  491.117985][T16896] Code: 00 00 00 00 ad de 49 39 c4 0f 84 92 00 00 00 48 b8 22 01 00 00 00 00 ad de 49 39 c5 0f 84 b8 00 00 00 4c 89 ef e8 77 4c 00 ff <4d> 8b 6d 00 49 39 ed 0f 85 8f 00 00 00 49 8d 7c 24 08 e8 60 4c 00
+[  491.118003][T16896] RSP: 0018:ffffc9000902f7d0 EFLAGS: 00010202
+[  491.124542][    C1] RIP: 0010:__list_del_entry_valid+0x59/0x8e
+[  491.130507][T16896] RAX: 0000000000000afb RBX: ffff888120ab9e00 RCX: ffffffff86d9d6b0
+[  491.136850][    C1] Code: 00 00 00 00 ad de 49 39 c4 0f 84 92 00 00 00 48 b8 22 01 00 00 00 00 ad de 49 39 c5 0f 84 b8 00 00 00 4c 89 ef e8 77 4c 00 ff <4d> 8b 6d 00 49 39 ed 0f 85 8f 00 00 00 49 8d 7c 24 08 e8 60 4c 00
+[  491.141504][T16896] RDX: 0000000000000000 RSI: ffff88808aa81a01 RDI: 0000000000ffff88
+[  491.152402][    C1] RSP: 0018:ffffc90000d08d18 EFLAGS: 00010002
+[  491.163177][T16896] RBP: ffff88808aa81a05 R08: 0000000000000000 R09: 0000000000ffff88
+[  491.183561][    C1] RAX: 0000000000000985 RBX: ffff8880a6a21a00 RCX: ffffffff86d9d6b0
+[  491.189647][T16896] R10: 0000888120ab9e48 R11: 0000000000ffff8f R12: 80ae4b8ef8ffff88
+[  491.195641][    C1] RDX: 0000000000000000 RSI: ffff88812c12d311 RDI: 0000000000ffff88
+[  491.203601][T16896] R13: 0000000000ffff88 R14: ffff88808aa81a00 R15: ffff8880ae4b8100
+[  491.223211][    C1] RBP: ffff88812c12d315 R08: 0000000000000000 R09: 0000000000ffff88
+[  491.231595][T16896] FS:  0000000000000000(0000) GS:ffff88812c000000(0000) knlGS:0000000000000000
+[  491.237646][    C1] R10: 0000000000000000 R11: 0000000000ffff8f R12: 808a92f0f0ffff88
+[  491.245640][T16896] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+[  491.253729][    C1] R13: 0000000000ffff88 R14: ffff88812c12d310 R15: ffff88812c12d310
+[  491.261774][T16896] CR2: 0000000100ffffc9 CR3: 0000000005a23000 CR4: 00000000001406f0
+[  491.261801][T16896] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
+[  491.269817][    C1] FS:  00007f0364420700(0000) GS:ffff88812c100000(0000) knlGS:0000000000000000
+[  491.278022][T16896] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
+[  491.286501][    C1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+[  491.295634][T16896] Kernel panic - not syncing: Fatal exception
+[  491.303559][    C1] CR2: 0000000000ffff88 CR3: 000000008b30d000 CR4: 00000000001406e0
+[  491.371566][    C1] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
+[  491.381001][    C1] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
+[  491.388963][    C1] Call Trace:
+[  491.392229][    C1]  <IRQ>
+[  491.395101][    C1]  ? account_entity_enqueue+0x97/0xc0
+[  491.400496][    C1]  ? enqueue_entity+0x96/0x5a0
+[  491.405267][    C1]  ? enqueue_task_fair+0xa6/0x400
+[  491.410298][    C1]  ? activate_task+0x67/0x100
+[  491.414964][    C1]  ? ttwu_do_activate.isra.0+0x3b/0x50
+[  491.420410][    C1]  ? try_to_wake_up+0x3b5/0x6d0
+[  491.425252][    C1]  ? hrtimer_wakeup+0x48/0x60
+[  491.429918][    C1]  ? __hrtimer_run_queues+0x271/0x600
+[  491.435281][    C1]  ? hrtimer_active+0x1b0/0x1b0
+[  491.440135][    C1]  ? hrtimer_interrupt+0x226/0x490
+[  491.445250][    C1]  ? kvm_clock_read+0x14/0x30
+[  491.449926][    C1]  ? smp_apic_timer_interrupt+0xd8/0x270
+[  491.455551][    C1]  ? apic_timer_interrupt+0xf/0x20
+[  491.460641][    C1]  </IRQ>
+[  491.463582][    C1]  ? add_taint+0x2b/0x60
+[  491.467830][    C1]  ? oops_end+0x5c/0xe0
+[  491.471987][    C1]  ? no_context+0x2ce/0x5e0
+[  491.476522][    C1]  ? add_nops+0xa0/0xa0
+[  491.480696][    C1]  ? __bad_area_nosemaphore+0x7d/0x310
+[  491.486158][    C1]  ? do_page_fault+0x708/0xa52
+[  491.490934][    C1]  ? page_fault+0x34/0x40
+[  491.495274][    C1]  ? __list_del_entry_valid+0x59/0x8e
+[  491.500638][    C1]  ? __list_add+0x40/0xd0
+[  491.504960][    C1]  ? nf_tables_newflowtable+0xcee/0xf00
+[  491.510544][    C1]  ? nft_trans_alloc_gfp+0xc0/0xc0
+[  491.515659][    C1]  ? nfnetlink_rcv_batch+0x528/0xbd0
+[  491.520979][    C1]  ? __nla_validate_parse+0xa8/0x11d0
+[  491.526350][    C1]  ? security_capable+0x8a/0xa0
+[  491.531193][    C1]  ? ns_capable_common+0xad/0xc0
+[  491.536134][    C1]  ? __nla_parse+0x4b/0x60
+[  491.540562][    C1]  ? nfnetlink_rcv+0x269/0x290
+[  491.545330][    C1]  ? netlink_unicast+0x390/0x4c0
+[  491.550265][    C1]  ? netlink_sendmsg+0x4cf/0x8a0
+[  491.555209][    C1]  ? netlink_unicast+0x4c0/0x4c0
+[  491.560138][    C1]  ? sock_sendmsg+0x98/0xc0
+[  491.564640][    C1]  ? ____sys_sendmsg+0x493/0x4c0
+[  491.569580][    C1]  ? ___sys_sendmsg+0xb5/0x100
+[  491.574352][    C1]  ? __rcu_read_unlock+0x66/0x2f0
+[  491.579389][    C1]  ? __fget_files+0xa2/0x1c0
+[  491.583993][    C1]  ? __fget_light+0xc0/0x1a0
+[  491.588613][    C1]  ? __fdget+0x29/0x30
+[  491.592682][    C1]  ? sockfd_lookup_light+0xa5/0x100
+[  491.597879][    C1]  ? __sys_sendmsg+0x9b/0x150
+[  491.602559][    C1]  ? __x64_sys_sendmsg+0x4c/0x60
+[  491.607508][    C1]  ? do_syscall_64+0xc7/0x390
+[  491.612205][    C1]  ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
+[  491.618273][    C1] Modules linked in:
+[  491.622160][    C1] CR2: 0000000000ffff88
+[  491.627088][    C1] ---[ end trace a5ad8ea8946e7e65 ]---
+[  491.632562][    C1] RIP: 0010:__list_del_entry_valid+0x59/0x8e
+[  491.638548][    C1] Code: 00 00 00 00 ad de 49 39 c4 0f 84 92 00 00 00 48 b8 22 01 00 00 00 00 ad de 49 39 c5 0f 84 b8 00 00 00 4c 89 ef e8 77 4c 00 ff <4d> 8b 6d 00 49 39 ed 0f 85 8f 00 00 00 49 8d 7c 24 08 e8 60 4c 00
+[  491.658155][    C1] RSP: 0018:ffffc9000902f7d0 EFLAGS: 00010202
+[  491.664223][    C1] RAX: 0000000000000afb RBX: ffff888120ab9e00 RCX: ffffffff86d9d6b0
+[  491.672190][    C1] RDX: 0000000000000000 RSI: ffff88808aa81a01 RDI: 0000000000ffff88
+[  491.680164][    C1] RBP: ffff88808aa81a05 R08: 0000000000000000 R09: 0000000000ffff88
+[  491.688139][    C1] R10: 0000888120ab9e48 R11: 0000000000ffff8f R12: 80ae4b8ef8ffff88
+[  491.696109][    C1] R13: 0000000000ffff88 R14: ffff88808aa81a00 R15: ffff8880ae4b8100
+[  491.704086][    C1] FS:  00007f0364420700(0000) GS:ffff88812c100000(0000) knlGS:0000000000000000
+[  491.713021][    C1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+[  491.719605][    C1] CR2: 0000000000ffff88 CR3: 000000008b30d000 CR4: 00000000001406e0
+[  491.727579][    C1] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
+[  491.736171][    C1] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
+[  492.459000][T16896] BUG: unable to handle page fault for address: 000000000000ffff
+[  492.466825][T16896] #PF: supervisor write access in kernel mode
+[  492.472995][T16896] #PF: error_code(0x0002) - not-present page
+[  492.478964][T16896] PGD 0 P4D 0 
+[  492.482342][T16896] Oops: 0002 [#4] PREEMPT SMP
+[  492.487107][T16896] CPU: 0 PID: 16896 Comm: sh Tainted: G      D           5.6.0-rc1-syzkaller #0
+[  492.496489][T16896] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
+[  492.506675][T16896] RIP: 0010:__list_add_valid+0x6a/0x70
+[  492.512182][T16896] Code: e2 0f 85 e5 00 00 00 4c 39 ed 0f 84 c5 00 00 00 48 39 d5 0f 84 bc 00 00 00 e8 32 40 00 ff b8 01 00 00 00 5d 41 5c 58 ab ee a6 <80> 88 ff ff 00 00 41 55 41 54 55 48 89 fd 48 8b 7c 24 18 e8 fe 3f
+[  492.531896][T16896] RSP: 0018:ffffc90008fff888 EFLAGS: 00010013
+[  492.537953][T16896] RAX: 0000000000000000 RBX: ffffffff85a59580 RCX: ffffffff86d9d568
+[  492.545918][T16896] RDX: ffffffff85a59c20 RSI: ffffffff85a56429 RDI: ffffffff85a5642d
+[  492.553992][T16896] RBP: ffffffff85a56428 R08: 0000000000000000 R09: 0000ffff85a56428
+[  492.562088][T16896] R10: 0000c90008fff7a0 R11: 0000ffff85a5642f R12: ffffffff85a59c20
+[  492.570106][T16896] R13: ffffffff85a56428 R14: ffffffff85a56428 R15: ffffffff85a56420
+[  492.578078][T16896] FS:  0000000000000000(0000) GS:ffff88812c000000(0000) knlGS:0000000000000000
+[  492.586995][T16896] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+[  492.593671][T16896] CR2: 000000000000ffff CR3: 0000000005a23000 CR4: 00000000001406f0
+[  492.601792][T16896] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
+[  492.609813][T16896] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
+[  492.617810][T16896] Call Trace:
+[  492.621097][T16896]  ? __register_nmi_handler+0xd7/0x120
+[  492.626553][T16896]  ? native_stop_other_cpus+0x148/0x180
+[  492.632164][T16896]  ? panic+0x249/0x640
+[  492.636352][T16896]  ? vprintk_func+0x89/0x13a
+[  492.640970][T16896]  ? oops_end.cold+0x18/0x18
+[  492.645552][T16896]  ? no_context+0x2ce/0x5e0
+[  492.650055][T16896]  ? __bad_area_nosemaphore+0x7d/0x310
+[  492.655558][T16896]  ? do_page_fault+0x3e9/0xa52
+[  492.660451][T16896]  ? __rcu_read_unlock+0x66/0x2f0
+[  492.665475][T16896]  ? page_fault+0x34/0x40
+[  492.669809][T16896]  ? __list_del_entry_valid+0x59/0x8e
+[  492.675404][T16896]  ? release_pages+0x7a3/0x9b0
+[  492.680201][T16896]  ? free_pages_and_swap_cache+0x231/0x2a0
+[  492.686061][T16896]  ? tlb_flush_mmu+0x76/0x390
+[  492.690758][T16896]  ? tlb_finish_mmu+0x7f/0x230
+[  492.695592][T16896]  ? exit_mmap+0x15e/0x2f0
+[  492.700009][T16896]  ? mmput+0xe2/0x260
+[  492.704060][T16896]  ? do_exit+0x640/0x1880
+[  492.708624][T16896]  ? recalc_sigpending+0x4f/0xe0
+[  492.713642][T16896]  ? do_sigaltstack.constprop.0+0x2b5/0x390
+[  492.719533][T16896]  ? _copy_from_user+0x93/0xf0
+[  492.724302][T16896]  ? do_group_exit+0xae/0x1a0
+[  492.728997][T16896]  ? __x64_sys_exit_group+0x2b/0x30
+[  492.734242][T16896]  ? do_syscall_64+0xc7/0x390
+[  492.738925][T16896]  ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
+[  492.745030][T16896] Modules linked in:
+[  492.748945][T16896] CR2: 000000000000ffff
+[  492.753088][T16896] ---[ end trace a5ad8ea8946e7e66 ]---
+[  492.758542][T16896] RIP: 0010:__list_del_entry_valid+0x59/0x8e
+[  492.764661][T16896] Code: 00 00 00 00 ad de 49 39 c4 0f 84 92 00 00 00 48 b8 22 01 00 00 00 00 ad de 49 39 c5 0f 84 b8 00 00 00 4c 89 ef e8 77 4c 00 ff <4d> 8b 6d 00 49 39 ed 0f 85 8f 00 00 00 49 8d 7c 24 08 e8 60 4c 00
+[  492.784401][T16896] RSP: 0018:ffffc9000902f7d0 EFLAGS: 00010202
+[  492.790535][T16896] RAX: 0000000000000afb RBX: ffff888120ab9e00 RCX: ffffffff86d9d6b0
+[  492.798498][T16896] RDX: 0000000000000000 RSI: ffff88808aa81a01 RDI: 0000000000ffff88
+[  492.806482][T16896] RBP: ffff88808aa81a05 R08: 0000000000000000 R09: 0000000000ffff88
+[  492.814450][T16896] R10: 0000888120ab9e48 R11: 0000000000ffff8f R12: 80ae4b8ef8ffff88
+[  492.822415][T16896] R13: 0000000000ffff88 R14: ffff88808aa81a00 R15: ffff8880ae4b8100
+[  492.830394][T16896] FS:  0000000000000000(0000) GS:ffff88812c000000(0000) knlGS:0000000000000000
+[  492.839314][T16896] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+[  492.845895][T16896] CR2: 000000000000ffff CR3: 0000000005a23000 CR4: 00000000001406f0
+[  492.853893][T16896] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
+[  492.861856][T16896] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
+[  492.869878][T16896] Kernel panic - not syncing: Fatal exception
+[  492.876789][T16896] Kernel Offset: disabled
+[  492.881320][T16896] Rebooting in 86400 seconds..
diff --git a/pkg/report/testdata/linux/report/480 b/pkg/report/testdata/linux/report/480
new file mode 100644
index 000000000..4afe4cd49
--- /dev/null
+++ b/pkg/report/testdata/linux/report/480
@@ -0,0 +1,60 @@
+TITLE: BUG: unable to handle kernel NULL pointer dereference in handle_external_interrupt_irqoff
+
+[  202.652969][ T9969] BUG: kernel NULL pointer dereference, address: 0000000000000086
+[  202.660811][ T9969] #PF: supervisor instruction fetch in kernel mode
+[  202.667314][ T9969] #PF: error_code(0x0010) - not-present page
+[  202.673292][ T9969] PGD 42d21067 P4D 42d21067 PUD a442d067 PMD 0 
+[  202.679547][ T9969] Oops: 0010 [#1] PREEMPT SMP KASAN
+[  202.684751][ T9969] CPU: 1 PID: 9969 Comm: syz-executor.0 Not tainted 5.6.0-rc6-syzkaller #0
+[  202.685601][ T9967] ubi0: scanning is finished
+[  202.693464][ T9969] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
+[  202.693481][ T9969] RIP: 0010:0x86
+[  202.693499][ T9969] Code: Bad RIP value.
+[  202.693508][ T9969] RSP: 0018:ffffc90001b9f998 EFLAGS: 00010086
+[  202.693515][ T9969] RAX: ffffc90001b9f9c8 RBX: fffffe0000000000 RCX: 0000000000040000
+[  202.693520][ T9969] RDX: ffffc90002121000 RSI: 00000000000042cc RDI: 00000000000042cd
+[  202.693525][ T9969] RBP: 0000000000000ec0 R08: ffffffff839870a3 R09: ffffffff811c7eca
+[  202.693530][ T9969] R10: ffff88804b338000 R11: 0000000000000002 R12: dffffc0000000000
+[  202.693535][ T9969] R13: fffffe0000000ec8 R14: ffffffff880016f0 R15: fffffe0000000ecb
+[  202.693547][ T9969] FS:  00007f70cf831700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
+[  202.693552][ T9969] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+[  202.693558][ T9969] CR2: 000000000000005c CR3: 0000000098245000 CR4: 00000000001426e0
+[  202.693564][ T9969] Call Trace:
+[  202.693582][ T9969]  ? handle_external_interrupt_irqoff+0x154/0x280
+[  202.693597][ T9969]  ? handle_external_interrupt_irqoff+0x132/0x280
+[  202.693606][ T9969]  ? __irqentry_text_start+0x8/0x8
+[  202.693625][ T9969]  ? vcpu_enter_guest+0x6c77/0x9290
+[  202.811509][ T9969]  ? __kasan_slab_free+0x12e/0x1e0
+[  202.816609][ T9969]  ? kfree+0x10a/0x220
+[  202.820667][ T9969]  ? tomoyo_path_number_perm+0x525/0x690
+[  202.826289][ T9969]  ? security_file_ioctl+0x55/0xb0
+[  202.831397][ T9969]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
+[  202.837465][ T9969]  ? __lock_acquire+0xc5a/0x1bc0
+[  202.842409][ T9969]  ? mark_lock+0x107/0x1650
+[  202.846912][ T9969]  ? lock_acquire+0x154/0x250
+[  202.851580][ T9969]  ? rcu_lock_acquire+0x9/0x30
+[  202.856335][ T9969]  ? kvm_check_async_pf_completion+0x34e/0x360
+[  202.862486][ T9969]  ? vcpu_run+0x3a3/0xd50
+[  202.866823][ T9969]  ? kvm_arch_vcpu_ioctl_run+0x419/0x880
+[  202.872449][ T9969]  ? kvm_vcpu_ioctl+0x67c/0xa80
+[  202.877303][ T9969]  ? kvm_vm_release+0x50/0x50
+[  202.881990][ T9969]  ? __se_sys_ioctl+0xf9/0x160
+[  202.886873][ T9969]  ? do_syscall_64+0xf3/0x1b0
+[  202.891570][ T9969]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
+[  202.897636][ T9969] Modules linked in:
+[  202.901521][ T9969] CR2: 0000000000000086
+[  202.905670][ T9969] ---[ end trace e25748bb637f10e1 ]---
+[  202.911117][ T9969] RIP: 0010:0x86
+[  202.914666][ T9969] Code: Bad RIP value.
+[  202.918737][ T9969] RSP: 0018:ffffc90001b9f998 EFLAGS: 00010086
+[  202.924791][ T9969] RAX: ffffc90001b9f9c8 RBX: fffffe0000000000 RCX: 0000000000040000
+[  202.932770][ T9969] RDX: ffffc90002121000 RSI: 00000000000042cc RDI: 00000000000042cd
+[  202.940749][ T9969] RBP: 0000000000000ec0 R08: ffffffff839870a3 R09: ffffffff811c7eca
+[  202.948727][ T9969] R10: ffff88804b338000 R11: 0000000000000002 R12: dffffc0000000000
+[  202.956700][ T9969] R13: fffffe0000000ec8 R14: ffffffff880016f0 R15: fffffe0000000ecb
+[  202.964675][ T9969] FS:  00007f70cf831700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
+[  202.973600][ T9969] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+[  202.980175][ T9969] CR2: 000000000000005c CR3: 0000000098245000 CR4: 00000000001426e0
+[  202.988141][ T9969] Kernel panic - not syncing: Fatal exception
+[  202.995457][ T9969] Kernel Offset: disabled
+[  202.999782][ T9969] Rebooting in 86400 seconds..
diff --git a/pkg/report/testdata/linux/report/481 b/pkg/report/testdata/linux/report/481
new file mode 100644
index 000000000..26c293e62
--- /dev/null
+++ b/pkg/report/testdata/linux/report/481
@@ -0,0 +1,59 @@
+TITLE: BUG: unable to handle kernel NULL pointer dereference in handle_external_interrupt_irqoff
+
+[  418.945118][T17277] BUG: kernel NULL pointer dereference, address: 0000000000000086
+[  418.953273][T17277] #PF: supervisor instruction fetch in kernel mode
+[  418.959840][T17277] #PF: error_code(0x0010) - not-present page
+[  418.965805][T17277] PGD 8ae6c067 P4D 8ae6c067 PUD 9f526067 PMD 0 
+[  418.972059][T17277] Oops: 0010 [#1] PREEMPT SMP KASAN
+[  418.977254][T17277] CPU: 0 PID: 17277 Comm: syz-executor.5 Not tainted 5.6.0-rc6-syzkaller #0
+[  418.986036][T17277] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
+[  418.996104][T17277] RIP: 0010:0x86
+[  418.999641][T17277] Code: Bad RIP value.
+[  419.003683][T17277] RSP: 0018:ffffc90004b67998 EFLAGS: 00010086
+[  419.009742][T17277] RAX: ffffc90004b679c8 RBX: fffffe0000000000 RCX: 0000000000040000
+[  419.017735][T17277] RDX: ffffc90015729000 RSI: 0000000000003ac8 RDI: 0000000000003ac9
+[  419.025704][T17277] RBP: 0000000000000fd0 R08: ffffffff839870a3 R09: ffffffff811c7eca
+[  419.034180][T17277] R10: ffff88809744e200 R11: 0000000000000002 R12: dffffc0000000000
+[  419.042315][T17277] R13: fffffe0000000fd8 R14: ffffffff880017d0 R15: fffffe0000000fdb
+[  419.050284][T17277] FS:  00007f12dcc21700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
+[  419.059197][T17277] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+[  419.065767][T17277] CR2: 000000000000005c CR3: 0000000096823000 CR4: 00000000001426f0
+[  419.073802][T17277] Call Trace:
+[  419.077167][T17277]  ? handle_external_interrupt_irqoff+0x154/0x280
+[  419.083678][T17277]  ? handle_external_interrupt_irqoff+0x132/0x280
+[  419.090088][T17277]  ? call_function_interrupt+0x20/0x20
+[  419.095610][T17277]  ? vcpu_enter_guest+0x6c77/0x9290
+[  419.100811][T17277]  ? __kasan_slab_free+0x12e/0x1e0
+[  419.105914][T17277]  ? kfree+0x10a/0x220
+[  419.109968][T17277]  ? tomoyo_path_number_perm+0x525/0x690
+[  419.115708][T17277]  ? security_file_ioctl+0x55/0xb0
+[  419.120815][T17277]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
+[  419.126880][T17277]  ? __lock_acquire+0xc5a/0x1bc0
+[  419.131821][T17277]  ? mark_lock+0x107/0x1650
+[  419.136307][T17277]  ? lock_acquire+0x154/0x250
+[  419.140960][T17277]  ? rcu_lock_acquire+0x9/0x30
+[  419.145754][T17277]  ? kvm_check_async_pf_completion+0x34e/0x360
+[  419.151889][T17277]  ? vcpu_run+0x3a3/0xd50
+[  419.156223][T17277]  ? kvm_arch_vcpu_ioctl_run+0x419/0x880
+[  419.161831][T17277]  ? kvm_vcpu_ioctl+0x67c/0xa80
+[  419.166672][T17277]  ? kvm_vm_release+0x50/0x50
+[  419.171334][T17277]  ? __se_sys_ioctl+0xf9/0x160
+[  419.176101][T17277]  ? do_syscall_64+0xf3/0x1b0
+[  419.181374][T17277]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
+[  419.187428][T17277] Modules linked in:
+[  419.191318][T17277] CR2: 0000000000000086
+[  419.195478][T17277] ---[ end trace 4c5f669c48269d7c ]---
+[  419.200915][T17277] RIP: 0010:0x86
+[  419.204453][T17277] Code: Bad RIP value.
+[  419.208503][T17277] RSP: 0018:ffffc90004b67998 EFLAGS: 00010086
+[  419.214549][T17277] RAX: ffffc90004b679c8 RBX: fffffe0000000000 RCX: 0000000000040000
+[  419.222523][T17277] RDX: ffffc90015729000 RSI: 0000000000003ac8 RDI: 0000000000003ac9
+[  419.230473][T17277] RBP: 0000000000000fd0 R08: ffffffff839870a3 R09: ffffffff811c7eca
+[  419.238425][T17277] R10: ffff88809744e200 R11: 0000000000000002 R12: dffffc0000000000
+[  419.248025][T17277] R13: fffffe0000000fd8 R14: ffffffff880017d0 R15: fffffe0000000fdb
+[  419.255992][T17277] FS:  00007f12dcc21700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
+[  419.264907][T17277] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+[  419.271465][T17277] CR2: 000000000000005c CR3: 0000000096823000 CR4: 00000000001426f0
+[  419.279510][T17277] Kernel panic - not syncing: Fatal exception
+[  419.287150][T17277] Kernel Offset: disabled
+[  419.291486][T17277] Rebooting in 86400 seconds..
diff --git a/pkg/report/testdata/linux/report/482 b/pkg/report/testdata/linux/report/482
new file mode 100644
index 000000000..435bdfbba
--- /dev/null
+++ b/pkg/report/testdata/linux/report/482
@@ -0,0 +1,21 @@
+TITLE: INFO: task syz-executor can't die for more than 143 seconds.
+
+[  440.207852][ T1045] INFO: task syz-executor.1:12632 can't die for more than 143 seconds. 
+[  440.216128][ T1045] syz-executor.1  R  running task    29600 12632   8638 0x00004006 
+[  440.235983][ T1045] Call Trace: 
+[  440.239833][ T1045]  ? rcu_read_lock_sched_held+0x110/0x130 
+[  440.245566][ T1045]  ? __alloc_pages_nodemask+0x61b/0x8d0 
+[  440.257859][ T1045]  ? trace_hardirqs_on_thunk+0x1a/0x1c 
+[  440.263355][ T1045]  ? __alloc_pages_slowpath+0x28b0/0x28b0 
+[  440.275132][ T1045]  ? __sanitizer_cov_trace_const_cmp2+0x18/0x20 
+[  440.281816][ T1045]  ? alloc_pages_current+0x10f/0x210 
+[  440.287141][ T1045]  ? set_memory_decrypted+0x9/0x10 
+[  440.299038][ T1045]  ? arch_kexec_post_alloc_pages+0x9/0x10 
+[  440.304777][ T1045]  ? kimage_alloc_pages+0x1bc/0x210 
+[  440.314088][ T1045]  ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 
+[  440.322492][ T1045]  ? kimage_alloc_page+0x2c7/0x9f0 
+[  440.331622][ T1045]  ? kimage_load_segment+0x25d/0x740 
+[  440.336952][ T1045]  ? do_kexec_load+0x41a/0x600 
+[  440.343957][ T1045]  ? __x64_sys_kexec_load+0x1d5/0x260 
+[  440.353432][ T1045]  ? do_syscall_64+0xfd/0x680 
+[  440.360289][ T1045]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe