all: get pcBase from elf first which can be used for kaslr offset calc

4 files changed, 39 insertions, 0 deletions

diff --git a/pkg/cover/backend/backend.go b/pkg/cover/backend/backend.go
index bba483fa8..49f2f9508 100644
--- a/pkg/cover/backend/backend.go
+++ b/pkg/cover/backend/backend.go
@@ -6,6 +6,7 @@ package backend
 import (
 	"fmt"
 
+	"github.com/google/syzkaller/pkg/mgrconfig"
 	"github.com/google/syzkaller/sys/targets"
 )
 
@@ -79,3 +80,10 @@ func Make(target *targets.Target, vm, objDir, srcDir, buildDir string, splitBuil
 	}
 	return makeELF(target, objDir, srcDir, buildDir, delimiters, moduleObj, modules)
 }
+
+func GetPCBase(cfg *mgrconfig.Config) (uint64, error) {
+	if cfg.Target.OS == targets.Linux {
+		return getPCBase(cfg)
+	}
+	return 0, nil
+}
diff --git a/pkg/cover/backend/elf.go b/pkg/cover/backend/elf.go
index f4f288314..25536c170 100644
--- a/pkg/cover/backend/elf.go
+++ b/pkg/cover/backend/elf.go
@@ -8,9 +8,11 @@ import (
 	"encoding/binary"
 	"fmt"
 	"io"
+	"path/filepath"
 	"strings"
 
 	"github.com/google/syzkaller/pkg/log"
+	"github.com/google/syzkaller/pkg/mgrconfig"
 	"github.com/google/syzkaller/sys/targets"
 )
 
@@ -217,3 +219,22 @@ func elfGetCompilerVersion(path string) string {
 	}
 	return string(data[:])
 }
+
+func getPCBase(cfg *mgrconfig.Config) (uint64, error) {
+	bin := filepath.Join(cfg.KernelObj, cfg.SysTarget.KernelObject)
+	file, err := elf.Open(bin)
+	if err != nil {
+		return 0, err
+	}
+	defer file.Close()
+	allSymbols, err := file.Symbols()
+	if err != nil {
+		return 0, err
+	}
+	for _, sym := range allSymbols {
+		if sym.Name == "_stext" {
+			return sym.Value, nil
+		}
+	}
+	return 0, fmt.Errorf("no _stext symbol")
+}
diff --git a/pkg/cover/report.go b/pkg/cover/report.go
index 4a557c252..b41a96356 100644
--- a/pkg/cover/report.go
+++ b/pkg/cover/report.go
@@ -30,6 +30,10 @@ type Prog struct {
 
 type KernelModule = backend.KernelModule
 
+func GetPCBase(cfg *mgrconfig.Config) (uint64, error) {
+	return backend.GetPCBase(cfg)
+}
+
 func MakeReportGenerator(cfg *mgrconfig.Config, subsystem []mgrconfig.Subsystem,
 	modules []*KernelModule, rawCover bool) (*ReportGenerator, error) {
 	impl, err := backend.Make(cfg.SysTarget, cfg.Type, cfg.KernelObj,
diff --git a/pkg/rpcserver/rpcserver.go b/pkg/rpcserver/rpcserver.go
index 40ca9a316..0cb1e05a9 100644
--- a/pkg/rpcserver/rpcserver.go
+++ b/pkg/rpcserver/rpcserver.go
@@ -41,6 +41,7 @@ type Config struct {
 	PrintMachineCheck bool
 	Procs             int
 	Slowdown          int
+	PCBase            uint64
 }
 
 type Manager interface {
@@ -81,6 +82,10 @@ type Server struct {
 }
 
 func New(cfg *mgrconfig.Config, mgr Manager, debug bool) (*Server, error) {
+	pcBase, err := cover.GetPCBase(cfg)
+	if err != nil {
+		return nil, err
+	}
 	sandbox, err := flatrpc.SandboxToFlags(cfg.Sandbox)
 	if err != nil {
 		return nil, err
@@ -109,6 +114,7 @@ func New(cfg *mgrconfig.Config, mgr Manager, debug bool) (*Server, error) {
 		PrintMachineCheck: true,
 		Procs:             cfg.Procs,
 		Slowdown:          cfg.Timeouts.Slowdown,
+		PCBase:            pcBase,
 	}, mgr)
 }