On Tue, May 14, 2019 at 08:52:27PM +0100, Kieran Kunhya wrote: > On Tue, 14 May 2019 at 20:42, Michael Niedermayer <mich...@niedermayer.cc> > wrote: > > > Fixes: Timeout (33sec -> 78ms) > > Fixes: > > 14668/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LSCR_fuzzer-5767073352908800 > > > > Found-by: continuous fuzzing process > > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > Signed-off-by > > <https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by>: > > Michael Niedermayer <mich...@niedermayer.cc> > > --- > > libavcodec/pngdec.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c > > index 6a681be29d..78988d9e75 100644 > > --- a/libavcodec/pngdec.c > > +++ b/libavcodec/pngdec.c > > @@ -1535,6 +1535,9 @@ static int decode_frame_lscr(AVCodecContext *avctx, > > AVFrame *frame = data; > > int ret, nb_blocks, offset = 0; > > > > + if (avpkt->size < 2) > > + return AVERROR_INVALIDDATA; > > + > > > > Why not 1?
because the code reads 2 bytes next: nb_blocks = bytestream2_get_le16(gb); > Or maybe 3? > Or maybe 42? Its not checking for 3 or 42 or another number because the smallest valid frame that our decoder accepts is 2 bytes. In case you have a specification for LSCR, that would be interresting to read to see if it contains more constraints which would lead to a larger minimum size Thanks > > Random numbers to fix random samples are just absurd. > > Kieran > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB The misfortune of the wise is better than the prosperity of the fool. -- Epicurus
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