Re: [FFmpeg-devel] [PATCH 13/13] avformat/westwood_vqa: Check chunk size

From: Anton Khirnov <anton@khirnov.net>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH 13/13] avformat/westwood_vqa: Check chunk size
Date: Thu, 22 Sep 2022 15:01:05 +0200
Message-ID: <166385166529.3205.838741980740358047@lain.khirnov.net> (raw)
In-Reply-To: <20220918171410.31835-13-michael@niedermayer.cc>

Quoting Michael Niedermayer (2022-09-18 19:14:10)
> Fixes: signed integer overflow: 2147483647 + 1 cannot be represented in type 'int'
> Fixes: 50993/clusterfuzz-testcase-minimized-ffmpeg_dem_WSVQA_fuzzer-6593408795279360
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavformat/westwood_vqa.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/libavformat/westwood_vqa.c b/libavformat/westwood_vqa.c
> index e3d2e2668c4..bd8df5e0b34 100644
> --- a/libavformat/westwood_vqa.c
> +++ b/libavformat/westwood_vqa.c
> @@ -274,6 +274,8 @@ static int wsvqa_read_packet(AVFormatContext *s,
>                          return AVERROR(EIO);
>  
>                      /* the decoder expects chunks to be 16-bit aligned */
> +                    if (wsvqa->vqfl_chunk_size == INT_MAX)
> +                        return AVERROR_INVALIDDATA;

IIUC this can only happen after the
  wsvqa->vqfl_chunk_size > 3 * (1 << 20)
check above was triggered. Then it makes more sense to change that code
to check chunk_size before setting wsvqa->vqfl_chunk_size.

-- 
Anton Khirnov
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