https://bugs.kde.org/show_bug.cgi?id=378622
Bug ID: 378622
Summary: False positive with GCC 6.3.1 and -funswitch-loops
(-O3)
Product: valgrind
Version: unspecified
Platform: Other
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: NOR
Component: memcheck
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
In FFmpeg we have the following false-report reported by valgrind memcheck:
==26438== Memcheck, a memory error detector
==26438== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==26438== Using Valgrind-3.13.0.SVN and LibVEX; rerun with -h for copyright
info
==26438== Command: ./ffmpeg_g -i tests/data/fate/vsynth3-svq1.mov -frames:v 1
-f null -
==26438==
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, mov,mp4,m4a,3gp,3g2,mj2, from 'tests/data/fate/vsynth3-svq1.mov':
Metadata:
major_brand : qt
minor_version : 512
compatible_brands: qt
Duration: 00:00:02.00, start: 0.000000, bitrate: 163 kb/s
Stream #0:0(eng): Video: svq1 (SVQ1 / 0x31515653), yuv410p(progressive),
34x34, 159 kb/s, 25 fps, 25 tbr, 12800 tbn, 12800 tbc (default)
Metadata:
handler_name : DataHandler
encoder : Lavc svq1
Stream mapping:
Stream #0:0 -> #0:0 (svq1 (native) -> wrapped_avframe (native))
Press [q] to stop, [?] for help
==26438== Use of uninitialised value of size 8
==26438== at 0xAA8C50: svq1_decode_block_intra (svq1dec.c:211)
==26438== by 0xAAA2DE: svq1_decode_frame (svq1dec.c:703)
==26438== by 0x7A6D17: avcodec_decode_video2 (decode.c:420)
==26438== by 0x7A7AA7: do_decode (decode.c:224)
==26438== by 0x7A7C41: avcodec_send_packet (decode.c:319)
==26438== by 0x4A73C0: decode (ffmpeg.c:2254)
==26438== by 0x4A73C0: decode_video (ffmpeg.c:2398)
==26438== by 0x4A8BCA: process_input_packet (ffmpeg.c:2633)
==26438== by 0x488D79: process_input (ffmpeg.c:4390)
==26438== by 0x488D79: transcode_step (ffmpeg.c:4501)
==26438== by 0x488D79: transcode (ffmpeg.c:4555)
==26438== by 0x488D79: main (ffmpeg.c:4760)
==26438==
==26438== Use of uninitialised value of size 8
==26438== at 0xAA8C7A: svq1_decode_block_intra (svq1dec.c:211)
==26438== by 0xAAA2DE: svq1_decode_frame (svq1dec.c:703)
==26438== by 0x7A6D17: avcodec_decode_video2 (decode.c:420)
==26438== by 0x7A7AA7: do_decode (decode.c:224)
==26438== by 0x7A7C41: avcodec_send_packet (decode.c:319)
==26438== by 0x4A73C0: decode (ffmpeg.c:2254)
==26438== by 0x4A73C0: decode_video (ffmpeg.c:2398)
==26438== by 0x4A8BCA: process_input_packet (ffmpeg.c:2633)
==26438== by 0x488D79: process_input (ffmpeg.c:4390)
==26438== by 0x488D79: transcode_step (ffmpeg.c:4501)
==26438== by 0x488D79: transcode (ffmpeg.c:4555)
==26438== by 0x488D79: main (ffmpeg.c:4760)
==26438==
==26438== Use of uninitialised value of size 8
==26438== at 0xAA8CA6: svq1_decode_block_intra (svq1dec.c:211)
==26438== by 0xAAA2DE: svq1_decode_frame (svq1dec.c:703)
==26438== by 0x7A6D17: avcodec_decode_video2 (decode.c:420)
==26438== by 0x7A7AA7: do_decode (decode.c:224)
==26438== by 0x7A7C41: avcodec_send_packet (decode.c:319)
==26438== by 0x4A73C0: decode (ffmpeg.c:2254)
==26438== by 0x4A73C0: decode_video (ffmpeg.c:2398)
==26438== by 0x4A8BCA: process_input_packet (ffmpeg.c:2633)
==26438== by 0x488D79: process_input (ffmpeg.c:4390)
==26438== by 0x488D79: transcode_step (ffmpeg.c:4501)
==26438== by 0x488D79: transcode (ffmpeg.c:4555)
==26438== by 0x488D79: main (ffmpeg.c:4760)
==26438==
==26438== Use of uninitialised value of size 8
==26438== at 0xAA8CCE: svq1_decode_block_intra (svq1dec.c:211)
==26438== by 0xAAA2DE: svq1_decode_frame (svq1dec.c:703)
==26438== by 0x7A6D17: avcodec_decode_video2 (decode.c:420)
==26438== by 0x7A7AA7: do_decode (decode.c:224)
==26438== by 0x7A7C41: avcodec_send_packet (decode.c:319)
==26438== by 0x4A73C0: decode (ffmpeg.c:2254)
==26438== by 0x4A73C0: decode_video (ffmpeg.c:2398)
==26438== by 0x4A8BCA: process_input_packet (ffmpeg.c:2633)
==26438== by 0x488D79: process_input (ffmpeg.c:4390)
==26438== by 0x488D79: transcode_step (ffmpeg.c:4501)
==26438== by 0x488D79: transcode (ffmpeg.c:4555)
==26438== by 0x488D79: main (ffmpeg.c:4760)
==26438==
Output #0, null, to 'pipe:':
Metadata:
major_brand : qt
minor_version : 512
compatible_brands: qt
encoder : Lavf57.72.100
Stream #0:0(eng): Video: wrapped_avframe, yuv410p, 34x34, q=2-31, 200 kb/s,
25 fps, 25 tbn, 25 tbc (default)
Metadata:
handler_name : DataHandler
encoder : Lavc57.92.100 wrapped_avframe
frame= 1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A speed=0.24x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing
overhead: unknown
==26438==
==26438== HEAP SUMMARY:
==26438== in use at exit: 18,644 bytes in 7 blocks
==26438== total heap usage: 1,168 allocs, 1,161 frees, 426,378 bytes
allocated
==26438==
==26438== LEAK SUMMARY:
==26438== definitely lost: 0 bytes in 0 blocks
==26438== indirectly lost: 0 bytes in 0 blocks
==26438== possibly lost: 0 bytes in 0 blocks
==26438== still reachable: 18,644 bytes in 7 blocks
==26438== suppressed: 0 bytes in 0 blocks
==26438== Rerun with --leak-check=full to see details of leaked memory
==26438==
==26438== For counts of detected and suppressed errors, rerun with: -v
==26438== Use --track-origins=yes to see where uninitialised values come from
==26438== ERROR SUMMARY: 136 errors from 4 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-unswitch-loops or with clang.
The source code can be found in libavcodec/svq1dec.c
(http://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavcodec/svq1dec.c;hb=HEAD)
and sample is attached to this report.
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