Re: [FFmpeg-devel] [PATCH 3/5] avcodec/dcadec: Do not explode EAGAIN

[Michael Niedermayer <michael@niedermayer.cc>]

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On Mon, Sep 18, 2023 at 08:24:25PM -0300, James Almer wrote:
> On 9/18/2023 7:35 PM, Michael Niedermayer wrote:
> > Fixes: out of array access
> > Fixes: 62164/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DCA_fuzzer-6041088751960064
> > 
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >   libavcodec/dcadec.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/libavcodec/dcadec.c b/libavcodec/dcadec.c
> > index 3e3e3053bbe..070a9ae094d 100644
> > --- a/libavcodec/dcadec.c
> > +++ b/libavcodec/dcadec.c
> > @@ -221,7 +221,7 @@ static int dcadec_decode_frame(AVCodecContext *avctx, AVFrame *frame,
> >                       && (prev_packet & DCA_PACKET_XLL)
> >                       && (s->packet & DCA_PACKET_CORE))
> >                       s->packet |= DCA_PACKET_XLL | DCA_PACKET_RECOVERY;
> > -                else if (ret == AVERROR(ENOMEM) || (avctx->err_recognition & AV_EF_EXPLODE))
> > +                else if (ret == AVERROR(ENOMEM) || (avctx->err_recognition & AV_EF_EXPLODE) && ret != AVERROR(EAGAIN))
> >                       return ret;
> >               } else {
> >                   s->packet |= DCA_PACKET_XLL;
> 
> Maybe instead do
> 
> > diff --git a/libavcodec/dcadec.c b/libavcodec/dcadec.c
> > index 3e3e3053bb..3926115f21 100644
> > --- a/libavcodec/dcadec.c
> > +++ b/libavcodec/dcadec.c
> > @@ -217,11 +217,10 @@ static int dcadec_decode_frame(AVCodecContext *avctx, AVFrame *frame,
> >          if (asset && (asset->extension_mask & DCA_EXSS_XLL)) {
> >              if ((ret = ff_dca_xll_parse(&s->xll, input, asset)) < 0) {
> >                  // Conceal XLL synchronization error
> > -                if (ret == AVERROR(EAGAIN)
> > -                    && (prev_packet & DCA_PACKET_XLL)
> > -                    && (s->packet & DCA_PACKET_CORE))
> > -                    s->packet |= DCA_PACKET_XLL | DCA_PACKET_RECOVERY;
> > -                else if (ret == AVERROR(ENOMEM) || (avctx->err_recognition & AV_EF_EXPLODE))
> > +                if (ret == AVERROR(EAGAIN) {
> > +                    if ((prev_packet & DCA_PACKET_XLL) && (s->packet & DCA_PACKET_CORE))
> > +                        s->packet |= DCA_PACKET_XLL | DCA_PACKET_RECOVERY;
> > +                } else if (ret == AVERROR(ENOMEM) || (avctx->err_recognition & AV_EF_EXPLODE))
> >                      return ret;
> >              } else {
> >                  s->packet |= DCA_PACKET_XLL;
> 
> So EAGAIN is handled in one place.

ok will apply with you as author as its your change now

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Everything should be made as simple as possible, but not simpler.
-- Albert Einstein

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