[FFmpeg-devel] [PATCH 2/3] avcodec/iff: Check ham vs bpp
Michael Niedermayer
michael at niedermayer.cc
Sun Jun 23 11:45:56 EEST 2019
On Sun, Jun 23, 2019 at 06:33:02PM +1000, Peter Ross wrote:
> On Sun, Jun 23, 2019 at 12:30:54AM +0200, Michael Niedermayer wrote:
> > This checks the ham value much stricter and avoids hitting cases which cannot be reached
> > with data from the libavformat demuxer.
> >
> > Fixes: out of array access
> > Fixes: 15320/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_IFF_ILBM_fuzzer-5080476840099840
> > Fixes: 15423/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_IFF_ILBM_fuzzer-5630765833912320
> >
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > ---
> > libavcodec/iff.c | 15 ++++++++++++---
> > 1 file changed, 12 insertions(+), 3 deletions(-)
> >
> > diff --git a/libavcodec/iff.c b/libavcodec/iff.c
> > index b43bd507b3..b065bbe598 100644
> > --- a/libavcodec/iff.c
> > +++ b/libavcodec/iff.c
> > @@ -280,6 +280,18 @@ static int extract_header(AVCodecContext *const avctx,
> > for (i = 0; i < 16; i++)
> > s->tvdc[i] = bytestream_get_be16(&buf);
> >
> > + if (s->ham) {
> > + if (s->bpp > 8) {
> > + av_log(avctx, AV_LOG_ERROR, "Invalid number of hold bits for HAM: %u\n", s->ham);
> > + s->ham = 0;
> > + return AVERROR_INVALIDDATA;
> > + } if (s->ham != (s->bpp > 6 ? 6 : 4)) {
> > + av_log(avctx, AV_LOG_ERROR, "Invalid number of hold bits for HAM: %u, BPP: %u\n", s->ham, s->bpp);
> > + s->ham = 0;
> > + return AVERROR_INVALIDDATA;
> > + }
> > + }
>
> i am curious why we need to reset ham = 0? otherwise patch okay.
That was just so as not to leave an invalid value in the context. It is
very likely not needed, I will remove it.
>
> patch 1 and 3 okay.
will apply
thx
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety -- Benjamin Franklin
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