Re: [FFmpeg-devel] [PATCH] avcodec/pcm_rechunk_bsf: unref packet before putting a new one in

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH] avcodec/pcm_rechunk_bsf: unref packet before putting a new one in
Date: Wed, 30 Mar 2022 12:58:02 +0200
Message-ID: <20220330105802.GO2829255@pb2> (raw)
In-Reply-To: <62c40964-d827-d044-cec3-233bfc04aaf1@gmail.com>

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On Tue, Mar 29, 2022 at 06:33:06PM -0300, James Almer wrote:
> On 3/29/2022 6:24 PM, Michael Niedermayer wrote:
> > Fixes: memleak
> > Fixes: 45982/clusterfuzz-testcase-minimized-ffmpeg_BSF_PCM_RECHUNK_fuzzer-5562089618407424
> > 
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >   libavcodec/pcm_rechunk_bsf.c | 1 +
> >   1 file changed, 1 insertion(+)
> > 
> > diff --git a/libavcodec/pcm_rechunk_bsf.c b/libavcodec/pcm_rechunk_bsf.c
> > index 108d9e90b9..3f43934fe9 100644
> > --- a/libavcodec/pcm_rechunk_bsf.c
> > +++ b/libavcodec/pcm_rechunk_bsf.c
> > @@ -153,6 +153,7 @@ static int rechunk_filter(AVBSFContext *ctx, AVPacket *pkt)
> >               }
> >           }
> > +        av_packet_unref(s->in_pkt);
> 
> This looks to me like it revealed a bug in the code above, which is meant to
> ensure s->in_pkt will be blank at this point. It should be fixed there
> instead.

IIRC the problem was a input packet with size 0
the code seems to assume 0 meaning no packet

I can check more explicitly for that after ff_bsf_get_packet_ref()
and unref there, its more code through

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Its not that you shouldnt use gotos but rather that you should write
readable code and code with gotos often but not always is less readable

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