On Mon, Aug 06, 2018 at 09:50:57PM -0400, Ronald S. Bultje wrote: > Hi, > > On Mon, Aug 6, 2018 at 3:00 PM, Michael Niedermayer <mich...@niedermayer.cc> > wrote: > > > On Tue, Aug 07, 2018 at 01:05:51AM +0800, Ronald S. Bultje wrote: > > > Hi, > > > > > > On Sun, Aug 5, 2018, 9:17 AM Michael Niedermayer <mich...@niedermayer.cc > > > > > > wrote: > > > > > > > Fixes: Timeout > > > > Fixes: > > > > 9330/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ > > VP9_fuzzer-5707345857347584 > > > > > > > > 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/vp9.c | 3 +++ > > > > 1 file changed, 3 insertions(+) > > > > > > > > diff --git a/libavcodec/vp9.c b/libavcodec/vp9.c > > > > index b1178c9c0c..4ca51ec108 100644 > > > > --- a/libavcodec/vp9.c > > > > +++ b/libavcodec/vp9.c > > > > @@ -1302,6 +1302,9 @@ static int decode_tiles(AVCodecContext *avctx, > > > > memset(lflvl_ptr->mask, 0, > > > > sizeof(lflvl_ptr->mask)); > > > > } > > > > > > > > + if (td->c->end <= td->c->buffer && td->c->bits >= > > 0) { > > > > + return AVERROR_INVALIDDATA; > > > > + } > > > > if (s->pass == 2) { > > > > decode_sb_mem(td, row, col, lflvl_ptr, > > > > yoff2, uvoff2, BL_64X64); > > > > > > > > > > I don't think this matches spec. Implementations could use this to store > > > auxiliary data. > > > > This checks, or rather is intended to check for a premature end of the > > input. > > Am i missing something? because a premature end of input seems not to lead > > to more (auxiliary or other) data in the input. > > > Hm, I misread it, sorry about that, my bad. Please ignore my first review. >
> Is end == buffer && bits == 0 something that can happen on valid input if > things just align properly? Otherwise looks OK. The same condition is used in vp5/6/8. I think this condition only occurs if the input ends. The part i do not know is if such premature ends might be a "valid compression" Either way, if this check misbehaves for a valid file then it should be reverted/removed unless its improv-able and improved. [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB I have never wished to cater to the crowd; for what I know they do not approve, and what they approve I do not know. -- Epicurus
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