Re: [FFmpeg-devel] [PATCH 1/2] avformat/matroskadec: Fix infinite loop with bz decompression

From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] [PATCH 1/2] avformat/matroskadec: Fix infinite loop with bz decompression
Date: Fri, 4 Feb 2022 04:29:18 +0100
Message-ID: <AM7PR03MB666025C57C0ABF5E599785528F299@AM7PR03MB6660.eurprd03.prod.outlook.com> (raw)
In-Reply-To: <20220204005811.5459-1-michael@niedermayer.cc>

Michael Niedermayer:
> Fixes: Infinite loop
> Fixes: 43932/clusterfuzz-testcase-minimized-ffmpeg_dem_MATROSKA_fuzzer-6175167573786624
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavformat/matroskadec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
> index d165f6ab90..5a9acfb247 100644
> --- a/libavformat/matroskadec.c
> +++ b/libavformat/matroskadec.c
> @@ -1742,7 +1742,7 @@ static int matroska_decode_buffer(uint8_t **buf, int *buf_size,
>      case MATROSKA_TRACK_ENCODING_COMP_BZLIB:
>      {
>          bz_stream bzstream = { 0 };
> -        if (BZ2_bzDecompressInit(&bzstream, 0, 0) != BZ_OK)
> +        if (!pkt_size || BZ2_bzDecompressInit(&bzstream, 0, 0) != BZ_OK)
>              return -1;
>          bzstream.next_in  = data;
>          bzstream.avail_in = isize;

I see nothing in the zlib-API manual that would preclude this from
happening with zlib, too, so it should be checked there, too.
LGTM apart from that.

- Andreas
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