Re: [FFmpeg-devel] [PATCH v2] lavc/hevc_ps: fix process failed when SPS before VPS in hvcC

[wangyaqiang <1035567130@qq.com>]

> 2022年10月15日 07:00，Michael Niedermayer <michael@niedermayer.cc> 写道：
> 
> On Fri, Oct 14, 2022 at 06:13:14PM +0800, wangyaqiang wrote:
>> 
>> 
>>> 2022年9月27日 04:21，Michael Niedermayer <michael@niedermayer.cc> 写道：
>>> 
>>> On Mon, Sep 26, 2022 at 05:38:14PM +0800, 1035567130@qq.com wrote:
>>>> From: Wang Yaqiang <wangyaqiang03@kuaishou.com>
>>>> 
>>>> In some videos, SPS will be stored before VPS in hvcC box,
>>>> parse SPS does not depend on VPS, so the video is expected to be processed normally.
>>>> Added "parsed_vps" parameter to indicate whether VPS have been parsed.
>>>> Only VPS have been parsed can be verified during SPS parsing.
>>>> 
>>>> Signed-off-by: Wang Yaqiang <wangyaqiang03@kuaishou.com>
>>>> ---
>>>> libavcodec/hevc_ps.c | 3 +--
>>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>> 
>>> This causes segfaults
>>> 
>>> ==816== Invalid read of size 8
>>> ==816==    at 0xFAF178: hevc_parse (in ffmpeg_g)
>>> ==816==    by 0xA7A2A6: av_parser_parse2 (in ffmpeg_g)
>>> ==816==    by 0x5FC388: parse_packet (in ffmpeg_g)
>>> ==816==    by 0x5FDC5D: read_frame_internal (in ffmpeg_g)
>>> ==816==    by 0x5FFA10: avformat_find_stream_info (in ffmpeg_g)
>>> ==816==    by 0x2F6054: open_input_file (in ffmpeg_g)
>>> ==816==    by 0x2FC6AB: ffmpeg_parse_options (in ffmpeg_g)
>>> ==816==    by 0x2E8A34: main (in ffmpeg_g)
>>> ==816==  Address 0x8 is not stack'd, malloc'd or (recently) free'd
>>> 
>>> 
>>> [...]
>> 
>> Excuse me, we have run tests on our own business and have not found this problem, but it is a hidden risk,really hope you can tell me how to reproduce this problem. Thanks
> 
> heres a more complete stack trace, i willmail you the input sample privatly
> 

Thanks very much for the materials. Under the condition that vps is not strongly checked when parsing sps, it is necessary to determine whether vps is empty when vps is used. I submitted a new patch to fix the crash, but I feel that this way is a little trick,any good ideas?

> Trailing option(s) found in the command: may be ignored.
> [hevc @ 0x16a0ad40] Invalid NAL unit 0, skipping.
> [hevc @ 0x16a0ad40] PTL information too short
> ==24589==    at 0x12A19DF: VALGRIND_PRINTF_BACKTRACE (valgrind.h:6303)
> ==24589==    by 0x12A259D: av_log_default_callback (log.c:399)
> ==24589==    by 0x12A2844: av_vlog (log.c:434)
> ==24589==    by 0x12A26A3: av_log (log.c:413)
> ==24589==    by 0x10A7216: parse_ptl (hevc_ps.c:342)
> ==24589==    by 0x10A78B4: ff_hevc_decode_nal_vps (hevc_ps.c:503)
> ==24589==    by 0x10A579C: parse_nal_units (hevc_parser.c:212)
> ==24589==    by 0x10A5B46: hevc_parse (hevc_parser.c:331)
> ==24589==    by 0xB82366: av_parser_parse2 (parser.c:163)
> ==24589==    by 0x61BD17: parse_packet (demux.c:1140)
> ==24589==    by 0x61C936: read_frame_internal (demux.c:1334)
> ==24589==    by 0x6217A7: avformat_find_stream_info (demux.c:2612)
> ==24589==    by 0x246A51: open_input_file (ffmpeg_opt.c:1315)
> ==24589==    by 0x255E38: open_files (ffmpeg_opt.c:3703)
> ==24589==    by 0x255FEC: ffmpeg_parse_options (ffmpeg_opt.c:3742)
> ==24589==    by 0x26EFEE: main (ffmpeg.c:4236)
> [hevc @ 0x16a0ad40] VPS 0 does not exist
> ==24589== Invalid read of size 8
> ==24589==    at 0x10A5189: hevc_parse_slice_header (hevc_parser.c:88)
> ==24589==    by 0x10A584E: parse_nal_units (hevc_parser.c:245)
> ==24589==    by 0x10A5B46: hevc_parse (hevc_parser.c:331)
> ==24589==    by 0xB82366: av_parser_parse2 (parser.c:163)
> ==24589==    by 0x61BD17: parse_packet (demux.c:1140)
> ==24589==    by 0x61C936: read_frame_internal (demux.c:1334)
> ==24589==    by 0x6217A7: avformat_find_stream_info (demux.c:2612)
> ==24589==    by 0x246A51: open_input_file (ffmpeg_opt.c:1315)
> ==24589==    by 0x255E38: open_files (ffmpeg_opt.c:3703)
> ==24589==    by 0x255FEC: ffmpeg_parse_options (ffmpeg_opt.c:3742)
> ==24589==    by 0x26EFEE: main (ffmpeg.c:4236)
> ==24589==  Address 0x8 is not stack'd, malloc'd or (recently) free'd
> ==24589== 
> ==24589== 
> ==24589== Process terminating with default action of signal 11 (SIGSEGV)
> ==24589==  Access not within mapped region at address 0x8
> ==24589==    at 0x10A5189: hevc_parse_slice_header (hevc_parser.c:88)
> ==24589==    by 0x10A584E: parse_nal_units (hevc_parser.c:245)
> ==24589==    by 0x10A5B46: hevc_parse (hevc_parser.c:331)
> ==24589==    by 0xB82366: av_parser_parse2 (parser.c:163)
> ==24589==    by 0x61BD17: parse_packet (demux.c:1140)
> ==24589==    by 0x61C936: read_frame_internal (demux.c:1334)
> ==24589==    by 0x6217A7: avformat_find_stream_info (demux.c:2612)
> ==24589==    by 0x246A51: open_input_file (ffmpeg_opt.c:1315)
> ==24589==    by 0x255E38: open_files (ffmpeg_opt.c:3703)
> ==24589==    by 0x255FEC: ffmpeg_parse_options (ffmpeg_opt.c:3742)
> ==24589==    by 0x26EFEE: main (ffmpeg.c:4236)
> 
> [...]
> 
> -- 
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> 
> Concerning the gods, I have no means of knowing whether they exist or not
> or of what sort they may be, because of the obscurity of the subject, and
> the brevity of human life -- Protagoras
> 
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