debug/elf: guard access to File.gnuVersym
The size of gnuVersym should be multiples of 2. If not, the input is
invalid. No Library and Version information is added to sym in this
case. The current implementation of gnuVersion does not report errors
for invalid input.
While at here, bring back the comment that states that the undef entry
at the beginning is skipped. This is not an off-by-one error.
No test case because the problem can only happen for invalid data. Let
the fuzzer find cases like this.
Fixes #56429.
Change-Id: Ia39ad8bd509088a81cc77f7a76e23185d40a5765
GitHub-Last-Rev:
3be0cc1b1522874cf5dc509678aa6a5658b6bad5
GitHub-Pull-Request: golang/go#56431
Reviewed-on: https://go-review.googlesource.com/c/go/+/445555
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Run-TryBot: Meng Zhuo <mzh@golangcn.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>