[FFmpeg-devel] [PATCH] lavc/ratecontrol: Fix error logging for parsing and evaluation of rc_eq

[Michael Niedermayer]

On Thu, Jul 30, 2020 at 02:42:30PM +0200, Alexander Strasser wrote:
> Don't pass a potential NULL pointer to av_log, instead use a default
> in the rc_eq AVOption definitions. Now the context variable always
> holds a string; even if it's the default expression.
> 
> Note this also fixes the evaluation error path, where a similar
> av_log references the rc_eq string from the context too.
> ---
>  libavcodec/mpegvideo.h   | 2 +-
>  libavcodec/ratecontrol.c | 3 +--
>  2 files changed, 2 insertions(+), 3 deletions(-)

crashes with:
./ffmpeg -i matrixbench_mpeg2.mpg -vcodec snow  -y file.avi
==22043== Invalid read of size 1
==22043==    at 0x4C32CF2: strlen (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==22043==    by 0x10A83AD: av_expr_parse (in ffmpeg-git/ffmpeg/ffmpeg_g)
==22043==    by 0x2858ED: ff_rate_control_init (in ffmpeg-git/ffmpeg/ffmpeg_g)
==22043==    by 0x28A668: encode_init (in ffmpeg-git/ffmpeg/ffmpeg_g)
==22043==    by 0xA7E2D0: avcodec_open2 (in ffmpeg-git/ffmpeg/ffmpeg_g)
==22043==    by 0x2F196A: init_output_stream.constprop.24 (in ffmpeg-git/ffmpeg/ffmpeg_g)
==22043==    by 0x2F383A: reap_filters (in ffmpeg-git/ffmpeg/ffmpeg_g)
==22043==    by 0x2F78D7: transcode (in ffmpeg-git/ffmpeg/ffmpeg_g)
==22043==    by 0x2D093B: main (in ffmpeg-git/ffmpeg/ffmpeg_g)
==22043==  Address 0x0 is not stack'd, malloc'd or (recently) free'd

if you cannot reproduce, say so and ill make a more detailed backtrace

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I know you won't believe me, but the highest form of Human Excellence is
to question oneself and others. -- Socrates
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