[FFmpeg-devel] [PATCH] Revert "avformat/mpegts: update stream info when PMT ES stream_type changes"

[Michael Niedermayer]

On Mon, Jun 09, 2025 at 02:25:51PM +0200, Michael Niedermayer wrote:
> This fixes mixing up contexts, use of uninitialized data and crashes.
> More specifically:
> 
> ==1001752== Conditional jump or move depends on uninitialised value(s)
> ==1001752==    at 0xA9ED82: avpriv_h264_has_num_reorder_frames (h264dec.c:64)
> ==1001752==    by 0x668C7E: has_decode_delay_been_guessed (demux.c:757)
> ==1001752==    by 0x66AB13: compute_pkt_fields (demux.c:1137)
> ==1001752==    by 0x66B2E9: parse_packet (demux.c:1265)
> ==1001752==    by 0x66BD84: read_frame_internal (demux.c:1449)
> ==1001752==    by 0x67085B: avformat_find_stream_info (demux.c:2692)
> ==1001752==    by 0x25157C: ifile_open (ffmpeg_demux.c:1814)
> ==1001752==    by 0x272B15: open_files (ffmpeg_opt.c:1366)
> ==1001752==    by 0x272D85: ffmpeg_parse_options (ffmpeg_opt.c:1415)
> ==1001752==    by 0x2925C9: main (ffmpeg.c:991)
> ==1001752==  Uninitialised value was created by a heap allocation
> ==1001752==    at 0x483E0F0: memalign (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==1001752==    by 0x483E212: posix_memalign (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==1001752==    by 0x14882CE: av_malloc (mem.c:107)
> ==1001752==    by 0x1463785: av_buffer_alloc (buffer.c:82)
> ==1001752==    by 0x146423F: pool_alloc_buffer (buffer.c:369)
> ==1001752==    by 0x14643C4: av_buffer_pool_get (buffer.c:407)
> ==1001752==    by 0x752C4B: buffer_pool_get (mpegts.c:1142)
> ==1001752==    by 0x7538F2: mpegts_push_data (mpegts.c:1407)
> ==1001752==    by 0x758893: handle_packet (mpegts.c:2909)
> ==1001752==    by 0x758E90: handle_packets (mpegts.c:3048)
> ==1001752==    by 0x759B1D: mpegts_read_packet (mpegts.c:3290)
> ==1001752==    by 0x6687A3: ff_read_packet (demux.c:649)
> ==1001752==    by 0x66B594: read_frame_internal (demux.c:1346)
> ==1001752==    by 0x67085B: avformat_find_stream_info (demux.c:2692)
> ==1001752==    by 0x25157C: ifile_open (ffmpeg_demux.c:1814)
> ==1001752==    by 0x272B15: open_files (ffmpeg_opt.c:1366)
> ==1001752==    by 0x272D85: ffmpeg_parse_options (ffmpeg_opt.c:1415)
> ==1001752==    by 0x2925C9: main (ffmpeg.c:991)
> 
> Found-by: Alexander A. Shvedov <shvedov at gmx.com>
> CC: Pavel Koshevoy <pkoshevoy at gmail.com>
> This reverts commit 0021484d05f9b0f032fa319399de6e24eea0c04f.
> ---
>  libavformat/mpegts.c    | 4 +---
>  tests/ref/fate/ts-demux | 4 ++--
>  2 files changed, 3 insertions(+), 5 deletions(-)

does anyone object to this ?

Pavel, are you ok with this being reverted or do you want to submit a
patch that puts this behind some runtime flag ?

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Why not whip the teacher when the pupil misbehaves? -- Diogenes of Sinope
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