debug/dwarf: handle malformed line table with bad program offset

Touch up the line table reader to ensure that it can detect and reject
an invalid program offset field in the table header.

Fixes #53329.

Change-Id: Ia8d684e909af3aca3014b4a3d0dfd431e3f5a9f0
Reviewed-on: https://go-review.googlesource.com/c/go/+/413814
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>

diff --git a/src/debug/dwarf/line.go b/src/debug/dwarf/line.go
index bb281fbdd93b71b5d4c901111829a0770e8a6859..4df4a1751f341ed049f6f184f7a2643ff41a5191 100644 (file)
--- a/src/debug/dwarf/line.go
+++ b/src/debug/dwarf/line.go
@@ -215,7 +215,11 @@ func (r *LineReader) readHeader(compDir string) error {
        } else {
                headerLength = Offset(buf.uint32())
        }
-       r.programOffset = buf.off + headerLength
+       programOffset := buf.off + headerLength
+       if programOffset > r.endOffset {
+               return DecodeError{"line", hdrOffset, fmt.Sprintf("malformed line table: program offset %d exceeds end offset %d", programOffset, r.endOffset)}
+       }
+       r.programOffset = programOffset
        r.minInstructionLength = int(buf.uint8())
        if r.version >= 4 {
                // [DWARF4 6.2.4]