SEGV bug at libavfilter/avf_showspectrum.c:1789:52 in showspectrumpic_request_frame in FFmpeg

[ZengYunxiang]

Summary of the bug:

Dear developers,

We found the following SEGV bug on FFmpeg(version N-113007-g8d24a28d06) when using showspectrumpic filter, please confirm.

The poc file(poc15ffmpeg) will be attached to this ticket.

How to reproduce:

git clone https://github.com/FFmpeg/FFmpeg.git ffmpeg
cd ffmpeg
./configure --cc=clang --cxx=clang++ --ld=clang --enable-debug --toolchain=clang-asan
make -j30

./ffmpeg_g -y -i poc15ffmpeg -filter_complex showspectrumpic tmp.mp4

ASAN Log:

AddressSanitizer:DEADLYSIGNAL
=================================================================
==439689==ERROR: AddressSanitizer: SEGV on unknown address (pc 0x560d7ae3c30f bp 0x7f1dc3afb580 sp 0x7f1dc3afb380 T3)
==439689==The signal is caused by a READ memory access.
==439689==Hint: this fault was caused by a dereference of a high value address (see register values below).  Disassemble the provided pc to learn which register was used.
    #0 0x560d7ae3c30f in showspectrumpic_request_frame /ffmpeg/libavfilter/avf_showspectrum.c:1789:52
    #1 0x560d7ae552f6 in ff_request_frame_to_filter /ffmpeg/libavfilter/avfilter.c:482:15
    #2 0x560d7ae51676 in forward_status_change /ffmpeg/libavfilter/avfilter.c:1147:19
    #3 0x560d7ae51676 in ff_filter_activate_default /ffmpeg/libavfilter/avfilter.c:1188:20
    #4 0x560d7ae51676 in ff_filter_activate /ffmpeg/libavfilter/avfilter.c:1341:11
    #5 0x560d7ae64817 in push_frame /ffmpeg/libavfilter/buffersrc.c:168:15
    #6 0x560d7ae64817 in av_buffersrc_close /ffmpeg/libavfilter/buffersrc.c:286:47
    #7 0x560d7ad51263 in send_eof /ffmpeg/fftools/ffmpeg_filter.c:2546:15
    #8 0x560d7ad51263 in filter_thread /ffmpeg/fftools/ffmpeg_filter.c:2811:19
    #9 0x560d7ad93c18 in task_wrapper /ffmpeg/fftools/ffmpeg_sched.c:2200:21
    #10 0x7f1dc6c1eac2  (/lib/x86_64-linux-gnu/libc.so.6+0x94ac2) (BuildId: a43bfc8428df6623cd498c9c0caeb91aec9be4f9)
    #11 0x7f1dc6cb0a3f  (/lib/x86_64-linux-gnu/libc.so.6+0x126a3f) (BuildId: a43bfc8428df6623cd498c9c0caeb91aec9be4f9)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /ffmpeg/libavfilter/avf_showspectrum.c:1789:52 in showspectrumpic_request_frame
Thread T3 (fc0) created by T0 here:
    #0 0x560d7acdff9c in __interceptor_pthread_create (/ffmpeg/ffmpeg_g+0x90cf9c) (BuildId: 8d6ccf457a75d047d11f9627d0b67208c2215c8c)
    #1 0x560d7ad8e161 in task_start /ffmpeg/fftools/ffmpeg_sched.c:403:11
    #2 0x560d7adace68 in transcode /ffmpeg/fftools/ffmpeg.c:922:11
    #3 0x560d7adace68 in main /ffmpeg/fftools/ffmpeg.c:1050:11
    #4 0x7f1dc6bb3d8f  (/lib/x86_64-linux-gnu/libc.so.6+0x29d8f) (BuildId: a43bfc8428df6623cd498c9c0caeb91aec9be4f9)

==439689==ABORTING

ffmpeg version:

# ./ffmpeg -version
ffmpeg version N-113007-g8d24a28d06 Copyright (c) 2000-2023 the FFmpeg developers
built with Ubuntu clang version 14.0.0-1ubuntu1.1
configuration: --cc=clang --cxx=clang++ --ld=clang --enable-debug --toolchain=clang-asan
libavutil      58. 34.100 / 58. 34.100
libavcodec     60. 35.100 / 60. 35.100
libavformat    60. 18.100 / 60. 18.100
libavdevice    60.  4.100 / 60.  4.100
libavfilter     9. 14.100 /  9. 14.100
libswscale      7.  6.100 /  7.  6.100
libswresample   4. 13.100 /  4. 13.100

Credit:

Discovered by Zeng Yunxiang.

Thanks for your time!

[ZengYunxiang]

POC file

[Michael Niedermayer]

Fixed by ab0fdaedd1e7224f7e84ea22fcbfaa4ca75a6c06