| Summary: | False positive with GCC 6.3.1 and -fno-ipa-cp-clone (-O3) | ||
|---|---|---|---|
| Product: | [Developer tools] valgrind | Reporter: | ux <heetahke> |
| Component: | memcheck | Assignee: | Julian Seward <jseward> |
| Status: | REPORTED --- | ||
| Severity: | normal | ||
| Priority: | NOR | ||
| Version: | unspecified | ||
| Target Milestone: | --- | ||
| Platform: | Other | ||
| OS: | Linux | ||
| Latest Commit: | Version Fixed In: | ||
In FFmpeg we have the following false-report reported by valgrind memcheck: ==28424== Memcheck, a memory error detector ==28424== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al. ==28424== Using Valgrind-3.13.0.SVN and LibVEX; rerun with -h for copyright info ==28424== Command: ./ffmpeg_g -f lavfi -i testsrc -frames:v 1 -c ffv1 -f null - ==28424== ffmpeg version N-85447-g8839cbf911 Copyright (c) 2000-2017 the FFmpeg developers built with gcc 6.3.1 (GCC) 20170306 configuration: --enable-gpl --enable-libx264 --enable-libass --enable-libfreetype --enable-fontconfig --assert-level=2 --samples=/home/ux/fate-samples --enable-libdc1394 --enable-libvpx libavutil 55. 60.101 / 55. 60.101 libavcodec 57. 92.100 / 57. 92.100 libavformat 57. 72.100 / 57. 72.100 libavdevice 57. 7.100 / 57. 7.100 libavfilter 6. 84.101 / 6. 84.101 libswscale 4. 7.100 / 4. 7.100 libswresample 2. 8.100 / 2. 8.100 libpostproc 54. 6.100 / 54. 6.100 Input #0, lavfi, from 'testsrc': Duration: N/A, start: 0.000000, bitrate: N/A Stream #0:0: Video: rawvideo (RGB[24] / 0x18424752), rgb24, 320x240 [SAR 1:1 DAR 4:3], 25 tbr, 25 tbn, 25 tbc Stream mapping: Stream #0:0 -> #0:0 (rawvideo (native) -> ffv1 (native)) Press [q] to stop, [?] for help Output #0, null, to 'pipe:': Metadata: encoder : Lavf57.72.100 Stream #0:0: Video: ffv1, bgr0, 320x240 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc Metadata: encoder : Lavc57.92.100 ffv1 ==28424== Thread 21: ==28424== Conditional jump or move depends on uninitialised value(s) ==28424== at 0x81196B: encode_line (ffv1enc_template.c:58) ==28424== by 0x81196B: encode_rgb_frame (ffv1enc_template.c:187) ==28424== by 0x815B34: encode_slice (ffv1enc.c:1067) ==28424== by 0xA069BA: worker (pthread_slice.c:93) ==28424== by 0x8C1E2E6: start_thread (in /usr/lib/libpthread-2.25.so) ==28424== by 0x8F2154E: clone (in /usr/lib/libc-2.25.so) ==28424== frame= 1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A speed=0.13x video:4kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown ==28424== ==28424== HEAP SUMMARY: ==28424== in use at exit: 18,644 bytes in 7 blocks ==28424== total heap usage: 2,642 allocs, 2,635 frees, 14,334,780 bytes allocated ==28424== ==28424== LEAK SUMMARY: ==28424== definitely lost: 0 bytes in 0 blocks ==28424== indirectly lost: 0 bytes in 0 blocks ==28424== possibly lost: 0 bytes in 0 blocks ==28424== still reachable: 18,644 bytes in 7 blocks ==28424== suppressed: 0 bytes in 0 blocks ==28424== Rerun with --leak-check=full to see details of leaked memory ==28424== ==28424== For counts of detected and suppressed errors, rerun with: -v ==28424== Use --track-origins=yes to see where uninitialised values come from ==28424== ERROR SUMMARY: 230400 errors from 1 contexts (suppressed: 0 from 0) Both valgrind stable (3.12.0) and current SVN (r16297, VEX r3344) are affected. I don't know if it's a regression. This is not reproducible when using -fno-ipa-cp-clone or with clang. The source code can be found in libavcodec/ffv1enc_template.c (http://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavcodec/ffv1enc_template.c;hb=HEAD). No sample are required to reproduce (see the testsrc command used in the log above).