On Mon, Jan 18, 2021 at 09:06:10PM +0100, Anton Khirnov wrote: > Quoting Michael Niedermayer (2021-01-17 00:07:26) > > Fixes: signed integer overflow: 80 * 92233009 cannot be represented in type > > 'int' > > Fixes: > > 26910/clusterfuzz-testcase-minimized-ffmpeg_dem_NISTSPHERE_fuzzer-6669100654919680 > > > > Found-by: continuous fuzzing process > > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > Signed-off-by: Michael Niedermayer <[email protected]> > > --- > > libavformat/nistspheredec.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/libavformat/nistspheredec.c b/libavformat/nistspheredec.c > > index 079369929f..fec5c88892 100644 > > --- a/libavformat/nistspheredec.c > > +++ b/libavformat/nistspheredec.c > > @@ -80,7 +80,9 @@ static int nist_read_header(AVFormatContext *s) > > > > avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate); > > > > - st->codecpar->block_align = > > st->codecpar->bits_per_coded_sample * st->codecpar->channels / 8; > > + if (st->codecpar->bits_per_coded_sample * > > (uint64_t)st->codecpar->channels / 8 > INT_MAX) > > + return AVERROR_INVALIDDATA; > > + st->codecpar->block_align = > > st->codecpar->bits_per_coded_sample * (uint64_t)st->codecpar->channels / 8; > > > > if (avio_tell(s->pb) > header_size) > > return AVERROR_INVALIDDATA; > > -- > > 2.17.1 > > Both bits_per_coded_sample and channels seem to be arbitrary ints, so > you are assuming sizeof(int) < sizeof(int64)
I wonder if we shouldnt limit these 2 fields in a platform independant way
But if we dont then the change below should do more correct checks
@@ -80,7 +80,11 @@ static int nist_read_header(AVFormatContext *s)
avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
- st->codecpar->block_align = st->codecpar->bits_per_coded_sample *
st->codecpar->channels / 8;
+ if (st->codecpar->bits_per_coded_sample < 0 ||
st->codecpar->channels <= 0 ||
+ st->codecpar->bits_per_coded_sample > UINT64_MAX /
st->codecpar->channels ||
+ st->codecpar->bits_per_coded_sample *
(uint64_t)st->codecpar->channels / 8 > INT_MAX)
+ return AVERROR_INVALIDDATA;
+ st->codecpar->block_align = st->codecpar->bits_per_coded_sample *
(uint64_t)st->codecpar->channels / 8;
if (avio_tell(s->pb) > header_size)
return AVERROR_INVALIDDATA;
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Breaking DRM is a little like attempting to break through a door even
though the window is wide open and the only thing in the house is a bunch
of things you dont want and which you would get tomorrow for free anyway
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