[FFmpeg-devel] [PATCH 3/7] avcodec/alsdec: Fix integer overflow with buffer number

[Reimar Döffinger]

On 21.06.2019, at 00:47, Michael Niedermayer <michael at niedermayer.cc> wrote:

> Fixes: signed integer overflow: 65313 * 65313 cannot be represented in type 'int'
> Fixes: 15290/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALS_fuzzer-5738074249625600
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
> libavcodec/alsdec.c | 2 ++
> 1 file changed, 2 insertions(+)
> 
> diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
> index 79d22b7c2b..8e0d3e5f83 100644
> --- a/libavcodec/alsdec.c
> +++ b/libavcodec/alsdec.c
> @@ -1990,6 +1990,8 @@ static av_cold int decode_init(AVCodecContext *avctx)
> 
>     // allocate quantized parcor coefficient buffer
>     num_buffers = sconf->mc_coding ? avctx->channels : 1;
> +    if (num_buffers * (uint64_t)num_buffers > INT_MAX)
> +        return AVERROR_INVALIDDATA;

It would be nice if it was clear which code this check protects, i.e. some connection between the check and the code that overflows.
I guess one might also ask if > 30 000 channels might not be something to catch and disallow earlier and generally...