On Wed, May 15, 2019 at 05:53:49PM +0200, Michael Niedermayer wrote: > 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
will apply the patch in the next days unless there are objections [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB While the State exists there can be no freedom; when there is freedom there will be no State. -- Vladimir Lenin
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