| Summary: | wcslen causes false(?) uninitialised value warnings | ||
|---|---|---|---|
| Product: | [Developer tools] valgrind | Reporter: | Anders Kaseorg <andersk> |
| Component: | memcheck | Assignee: | Julian Seward <jseward> |
| Status: | REPORTED --- | ||
| Severity: | normal | ||
| Priority: | NOR | ||
| Version: | 3.7.0 | ||
| Target Milestone: | --- | ||
| Platform: | Ubuntu | ||
| OS: | Linux | ||
| Latest Commit: | Version Fixed In: | ||
| Sentry Crash Report: | |||
Hmm, there was a patch drifting around, that fixed this. Not sure where it got to -- it either got filed as a bug, or is on the dev- or users- lists. Within the last month IIRC. I can't find from a quick look around those, though. |
On Ubuntu precise (libc6 2.15-0ubuntu9, valgrind 3.7.0-0ubuntu3), wcslen() sometimes causes uninitialised value warnings in what seems to be correct code. I think valgrind is getting confused by the optimized assembly implementations of wcslen that read the string in large blocks. $ cat test.c #include <stdio.h> #include <wchar.h> int main() { wchar_t tmp[10]; swprintf(tmp, 10, L"aaaaaaaa"); return wcslen(tmp); } $ gcc -m32 -g -Wall test.c -o test && valgrind --track-origins=yes ./test ==4735== Memcheck, a memory error detector ==4735== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al. ==4735== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info ==4735== Command: ./test ==4735== ==4735== Conditional jump or move depends on uninitialised value(s) ==4735== at 0x49B0461: __wcslen_sse2 (wcslen-sse2.S:57) ==4735== by 0x49264D2: (below main) (libc-start.c:226) ==4735== Uninitialised value was created by a stack allocation ==4735== at 0x804842A: main (test.c:4) ==4735== ==4735== Conditional jump or move depends on uninitialised value(s) ==4735== at 0x49B0527: __wcslen_sse2 (wcslen-sse2.S:128) ==4735== by 0x49264D2: (below main) (libc-start.c:226) ==4735== Uninitialised value was created by a stack allocation ==4735== at 0x804842A: main (test.c:4) ==4735== ==4735== Conditional jump or move depends on uninitialised value(s) ==4735== at 0x49B0545: __wcslen_sse2 (wcslen-sse2.S:139) ==4735== by 0x49264D2: (below main) (libc-start.c:226) ==4735== ==4735== ==4735== HEAP SUMMARY: ==4735== in use at exit: 0 bytes in 0 blocks ==4735== total heap usage: 0 allocs, 0 frees, 0 bytes allocated ==4735== ==4735== All heap blocks were freed -- no leaks are possible ==4735== ==4735== For counts of detected and suppressed errors, rerun with: -v ==4735== ERROR SUMMARY: 3 errors from 3 contexts (suppressed: 0 from 0) $ gcc -m64 -g -Wall test.c -o test && valgrind --track-origins=yes ./test ==4746== Memcheck, a memory error detector ==4746== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al. ==4746== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info ==4746== Command: ./test ==4746== ==4746== Conditional jump or move depends on uninitialised value(s) ==4746== at 0x4ED4031: wcslen (wcslen.S:53) ==4746== by 0x400572: main (test.c:7) ==4746== Uninitialised value was created by a stack allocation ==4746== at 0x400544: main (test.c:4) ==4746== ==4746== Conditional jump or move depends on uninitialised value(s) ==4746== at 0x4ED4199: wcslen (wcslen.S:172) ==4746== by 0x400572: main (test.c:7) ==4746== Uninitialised value was created by a stack allocation ==4746== at 0x400544: main (test.c:4) ==4746== ==4746== Conditional jump or move depends on uninitialised value(s) ==4746== at 0x4ED41A0: wcslen (wcslen.S:176) ==4746== by 0x400572: main (test.c:7) ==4746== Uninitialised value was created by a stack allocation ==4746== at 0x400544: main (test.c:4) ==4746== ==4746== ==4746== HEAP SUMMARY: ==4746== in use at exit: 0 bytes in 0 blocks ==4746== total heap usage: 0 allocs, 0 frees, 0 bytes allocated ==4746== ==4746== All heap blocks were freed -- no leaks are possible ==4746== ==4746== For counts of detected and suppressed errors, rerun with: -v ==4746== ERROR SUMMARY: 3 errors from 3 contexts (suppressed: 2 from 2)