debug/buildid: treat too large string as "not a Go executable"

If the length does not fit in int, saferio.ReadDataAt returns
io.ErrUnexpectedEOF. Treat is as an invalid format.

Fixes #68692.
For #68592.

Cq-Include-Trybots: luci.golang.try:gotip-linux-386-longtest
Change-Id: Ie856f29c907fd10e6d9b7dfbb6f0d8008a75a1c6
Reviewed-on: https://go-review.googlesource.com/c/go/+/602435
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

diff --git a/src/debug/buildinfo/buildinfo.go b/src/debug/buildinfo/buildinfo.go
index fa02344cd3f57227deed959cfbd5865da65ee246..f3d38b26e84af9701fdfb579979c74decbbee4be 100644 (file)
--- a/src/debug/buildinfo/buildinfo.go
+++ b/src/debug/buildinfo/buildinfo.go
@@ -295,6 +295,10 @@ func decodeString(x exe, addr uint64) (string, uint64, error) {
 
        b, err = readData(x, addr, length)
        if err != nil {
+               if err == io.ErrUnexpectedEOF {
+                       // Length too large to allocate. Clearly bogus value.
+                       return "", 0, errNotGoExe
+               }
                return "", 0, err
        }
        if uint64(len(b)) < length {