[FFmpeg-devel] [PATCH 1/4] avformat/asfdec_f: Fix overflow check in get_tag()

[Anton Khirnov]

Quoting Michael Niedermayer (2020-03-15 22:20:55)
> Fixes: signed integer overflow: 2 * 1210064928 cannot be represented in type 'int'
> Fixes: 20873/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5761116909338624
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavformat/asfdec_f.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavformat/asfdec_f.c b/libavformat/asfdec_f.c
> index 57dc3b09b9..3f19747d78 100644
> --- a/libavformat/asfdec_f.c
> +++ b/libavformat/asfdec_f.c
> @@ -321,7 +321,7 @@ static void get_tag(AVFormatContext *s, const char *key, int type, int len, int
>      int64_t off = avio_tell(s->pb);
>  #define LEN 22
>  
> -    if ((unsigned)len >= (UINT_MAX - LEN) / 2)
> +    if ((unsigned)len >= (INT_MAX - LEN) / 2)

Is the cast still necessary then?

-- 
Anton Khirnov