[FFmpeg-devel] [PATCH] avformat/rmdec.c: fix left shift of negative value in rm_sync()

[Michael Niedermayer]

On Sun, Sep 15, 2019 at 12:22:39AM -0300, James Almer wrote:
> Fixes ticket 8143.
> 
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
>  libavformat/rmdec.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/libavformat/rmdec.c b/libavformat/rmdec.c
> index c9abd38d33..ccdc38f98a 100644
> --- a/libavformat/rmdec.c
> +++ b/libavformat/rmdec.c
> @@ -724,8 +724,7 @@ static int rm_sync(AVFormatContext *s, int64_t *timestamp, int *flags, int *stre
>  
>              num = avio_rb16(pb);
>              *timestamp = avio_rb32(pb);
> -            mlti_id = (avio_r8(pb)>>1)-1<<16;
> -            mlti_id = FFMAX(mlti_id, 0);
> +            mlti_id = FFMAX((avio_r8(pb) >> 1) - 1, 0) << 16;

functions with sideeffects like moving some file pointer should
not be used in macros which may evaluate their arguments multiple
times

thx

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

No snowflake in an avalanche ever feels responsible. -- Voltaire
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