On Wed, Nov 16, 2022 at 12:49:10PM +0100, Tomas Härdin wrote: > sön 2022-11-13 klockan 00:44 +0100 skrev Michael Niedermayer: > > Fixes: signed integer overflow: -3741319169 - 9223372036823449370 > > cannot be represented in type 'long' > > Fixes: 51896/clusterfuzz-testcase-minimized-ffmpeg_dem_MXF_fuzzer- > > 513039428681728 > > > > Found-by: continuous fuzzing process > > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > > --- > > libavformat/mxfdec.c | 10 +++++++--- > > 1 file changed, 7 insertions(+), 3 deletions(-) > > > > diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c > > index e6118e141d..42109cb43a 100644 > > --- a/libavformat/mxfdec.c > > +++ b/libavformat/mxfdec.c > > @@ -100,7 +100,7 @@ typedef struct MXFPartition { > > uint64_t previous_partition; > > int index_sid; > > int body_sid; > > - int64_t this_partition; > > + uint64_t this_partition; > > int64_t essence_offset; ///< absolute offset of essence > > int64_t essence_length; > > int32_t kag_size; > > @@ -3519,8 +3519,12 @@ static void > > mxf_compute_essence_containers(AVFormatContext *s) > > p->essence_offset = p->first_essence_klv.offset; > > > > /* essence container spans to the next partition */ > > - if (x < mxf->partitions_count - 1) > > - p->essence_length = mxf- > > >partitions[x+1].this_partition - p->essence_offset; > > + if (x < mxf->partitions_count - 1) { > > + if (mxf->partitions[x+1].this_partition < p- > > >essence_offset) { > > + p->essence_length = -1; > > + } else > > + p->essence_length = mxf- > > >partitions[x+1].this_partition - p->essence_offset; > > + } > > A better solution might be to record the actual offset of the > partitions rather than relying on ThisPartition. Then we can guarantee > that they are strictly increasing.
do you mean that pack_ofs could be used here ? (this is within 8 byte of this_partition) for the files i checked or something else ? but as pack_ofs is signed that either means dealing with potentially negative or changing it to uint64_t or adding a new field and avio_tell() somewhere? thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB It is a danger to trust the dream we wish for rather than the science we have, -- Dr. Kenneth Brown
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