pkg/report: fix guilty file extraction

reportPrefixLen can become wrong after symbolization
if we symbolize any lines in the prefix.
Adjust reportPrefixLen during symbolization.

Automatic testing of this is problematic
because we would need to symbolize which requires
the object file with debug info.
Tested manually with syz-symbolize.

2 files changed, 13 insertions, 8 deletions

diff --git a/pkg/report/linux.go b/pkg/report/linux.go
index ff5878370..3e6ebebcf 100644
--- a/pkg/report/linux.go
+++ b/pkg/report/linux.go
@@ -271,11 +271,9 @@ func (ctx *linux) parseOutput(output []byte) (
 
 func (ctx *linux) Symbolize(rep *Report) error {
 	if ctx.vmlinux != "" {
-		symbolized, err := ctx.symbolize(rep.Report)
-		if err != nil {
+		if err := ctx.symbolize(rep); err != nil {
 			return err
 		}
-		rep.Report = symbolized
 	}
 	// We still do this even if we did not symbolize,
 	// because tests pass in already symbolized input.
@@ -290,19 +288,25 @@ func (ctx *linux) Symbolize(rep *Report) error {
 	return nil
 }
 
-func (ctx *linux) symbolize(text []byte) ([]byte, error) {
+func (ctx *linux) symbolize(rep *Report) error {
 	symb := symbolizer.NewSymbolizer()
 	defer symb.Close()
 	strip := ctx.stripPrefix(symb)
 	var symbolized []byte
-	s := bufio.NewScanner(bytes.NewReader(text))
+	s := bufio.NewScanner(bytes.NewReader(rep.Report))
+	prefix := rep.reportPrefixLen
 	for s.Scan() {
 		line := append([]byte{}, s.Bytes()...)
 		line = append(line, '\n')
-		line = symbolizeLine(symb.Symbolize, ctx.symbols, ctx.vmlinux, strip, line)
-		symbolized = append(symbolized, line...)
+		newLine := symbolizeLine(symb.Symbolize, ctx.symbols, ctx.vmlinux, strip, line)
+		if prefix > len(symbolized) {
+			prefix += len(newLine) - len(line)
+		}
+		symbolized = append(symbolized, newLine...)
 	}
-	return symbolized, nil
+	rep.Report = symbolized
+	rep.reportPrefixLen = prefix
+	return nil
 }
 
 func (ctx *linux) stripPrefix(symb *symbolizer.Symbolizer) string {
diff --git a/tools/syz-symbolize/symbolize.go b/tools/syz-symbolize/symbolize.go
index 8ce2f73ff..277e09066 100644
--- a/tools/syz-symbolize/symbolize.go
+++ b/tools/syz-symbolize/symbolize.go
@@ -52,6 +52,7 @@ func main() {
 	}
 	fmt.Printf("TITLE: %v\n", rep.Title)
 	fmt.Printf("CORRUPTED: %v (%v)\n", rep.Corrupted, rep.CorruptedReason)
+	fmt.Printf("MAINTAINERS: %v\n", rep.Maintainers)
 	fmt.Printf("\n")
 	os.Stdout.Write(rep.Report)
 }