From: Ian Lance Taylor <iant@golang.org>
Date: Tue, 23 Aug 2022 00:42:54 +0000 (-0700)
Subject: debug/plan9obj: don't crash on EOF before symbol type
X-Git-Tag: go1.20rc1~1446
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=fc0d423789e3a2e1f84801be14ac657d41c115e4;p=gostls13.git

debug/plan9obj: don't crash on EOF before symbol type

No debug/plan9obj test case because the problem can only happen for
invalid data. Let the fuzzer find cases like this.

For #47653
Fixes #54585

Change-Id: I8d3e15725b9bc09dd0e6f2750769987021f5e982
Reviewed-on: https://go-review.googlesource.com/c/go/+/425115
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Joseph Tsai <joetsai@digital-static.net>
---

diff --git a/src/debug/plan9obj/file.go b/src/debug/plan9obj/file.go
index aa25809148..2b83f9bdff 100644
--- a/src/debug/plan9obj/file.go
+++ b/src/debug/plan9obj/file.go
@@ -212,6 +212,9 @@ func walksymtab(data []byte, ptrsz int, fn func(sym) error) error {
 			p = p[4:]
 		}
 
+		if len(p) < 1 {
+			return &formatError{len(data), "unexpected EOF", nil}
+		}
 		typ := p[0] & 0x7F
 		s.typ = typ
 		p = p[1:]