On Tue, Sep 28, 2021 at 12:07:49AM -0300, James Almer wrote: > On 9/27/2021 7:37 PM, Michael Niedermayer wrote: > > Fixes: Timeout > > Fixes: > > 39089/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MSNSIREN_fuzzer-6677219854909440 > > > > Found-by: continuous fuzzing process > > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > > --- > > libavcodec/siren.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/libavcodec/siren.c b/libavcodec/siren.c > > index 7f2b4678608..708990d6654 100644 > > --- a/libavcodec/siren.c > > +++ b/libavcodec/siren.c > > @@ -718,6 +718,9 @@ static int siren_decode(AVCodecContext *avctx, void > > *data, > > if ((ret = init_get_bits8(gb, avpkt->data, avpkt->size)) < 0) > > return ret; > > + if (s->sample_rate_bits + 4 > get_bits_left(gb)) > > + return AVERROR_INVALIDDATA; > > This is not enough. You'll inevitably get another timeout in the future > unless you add a get_bits_left(gb) > 0 condition to the loop in > decode_envelope(). > And there should be at least four bits left after decode_envelope() returns, > so check for that too.
suggest increasing the threshold to include:
s->sample_rate_bits + s->number_of_regions + 4 + s->checksum_bits >
get_bits_left(gb)
hey michael are you only fuzzing AV_CODEC_ID_MSNSIREN?
i would expect this issue to occur for for the vanilla SIREN codec too?
-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
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