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Created attachment 541034 [details] Test prog for showing problem Description of problem: When running the attached program under valgrind it gives errors. Version-Release number of selected component (if applicable): glibc-2.14.90-19.x86_64 How reproducible: Every time, when compiled with -m64 with -m32 the errors goes away. Steps to Reproduce: 1. compile the attached program with gcc -m64 -lcrypt crypt_r.c 2. run it with valgrind ./a.out "$1$abcdef$" (In the above string $1$ can be substituted with $5$ or $6$ and will then point to same errors, but with sha256 and sha512 instead of md5) Actual results: Valgrind gives erorrs about conditional jumps depending on uninitialized value(s) Expected results: No errors.
I am not been able to reproduce this on AMD Phenom(tm) II, I have only seen it on Intel so far (i7 970).
It could likely be specific to the SSE2 path which is only going to be used on a specific set of processors. I'll probably do a test build which forces everything to the SSE2 path so that I can test/debug without needing to find a box with a specific processor variant.
The errors I get are: ==9710== Conditional jump or move depends on uninitialised value(s) ==9710== at 0x33E929624F: __stpncpy_sse2_unaligned (in /lib64/libc-2.14.90.so) ==9710== by 0x33F4E0208C: __sha256_crypt_r (in /lib64/libcrypt-2.14.90.so) ==9710== by 0x33F4E00E7F: crypt_r (in /lib64/libcrypt-2.14.90.so) ==9710== by 0x40063A: main (h.c:12) ==9710== ==9710== Conditional jump or move depends on uninitialised value(s) ==9710== at 0x33E92961B8: __stpncpy_sse2_unaligned (in /lib64/libc-2.14.90.so) ==9710== by 0x33F4E0208C: __sha256_crypt_r (in /lib64/libcrypt-2.14.90.so) ==9710== by 0x33F4E00E7F: crypt_r (in /lib64/libcrypt-2.14.90.so) ==9710== by 0x40063A: main (h.c:12) I've tried to build my own glibc with debug symbols, and I can easily reproduce it there. With glibc from git (fedora/2.14/master branch), valgrind seems to think the error is in movslq (%r11, %rcx,4), %rcx at line 1106 in strcpy.S in sysdeps/x86_64/multiarch/strcpy.S. when called by crypt/sha256-crypt.c:307 This is on an Intel core i7.
*** Bug 699917 has been marked as a duplicate of this bug. ***
This is an annoying, but harmless false positive warning. It's a well known issue with vangrind that occurs with highly optimized string routines utilizing SSE extensions. In theory it should be possible to suppress this warning, but I've never tried to use the valgrind user defined suppressions.