[FFmpeg-devel] [PATCH 3/4] avformat/wsddec: Fix undefined shift

[Reimar Döffinger]

On 08.06.2019, at 11:28, Michael Niedermayer <michael at niedermayer.cc> wrote:

> Fixes: left shift of 1 by 31 places cannot be represented in type 'int'
> Fixes: 15123/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5738039235575808
> 
> 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/wsddec.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavformat/wsddec.c b/libavformat/wsddec.c
> index dfa8014b1c..43660d4cea 100644
> --- a/libavformat/wsddec.c
> +++ b/libavformat/wsddec.c
> @@ -137,7 +137,7 @@ static int wsd_read_header(AVFormatContext *s)
>     if (!(channel_assign & 1)) {
>         int i;
>         for (i = 1; i < 32; i++)
> -            if (channel_assign & (1 << i))
> +            if (channel_assign & (1U << i))

I'd be in favour of switching these kind of checks to
(a>>i)&1
as this is a much less risky idiom and IMO it would be best to spread that style...