Quoting Michael Niedermayer (2022-09-29 00:35:09) > On Wed, Sep 28, 2022 at 05:16:05PM +0200, Anton Khirnov wrote: > > Quoting Michael Niedermayer (2022-09-22 20:08:51) > > > Fixes: signed integer overflow: 119760682 - -2084600173 cannot be > > > represented in type 'int' > > > Fixes: > > > 50993/clusterfuzz-testcase-minimized-ffmpeg_dem_VIVIDAS_fuzzer-6745781167587328 > > > > > > Found-by: continuous fuzzing process > > > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > > > --- > > > libavformat/vividas.c | 13 +++++++++++-- > > > 1 file changed, 11 insertions(+), 2 deletions(-) > > > > > > diff --git a/libavformat/vividas.c b/libavformat/vividas.c > > > index e9954f73ed0..e8efe49a5c0 100644 > > > --- a/libavformat/vividas.c > > > +++ b/libavformat/vividas.c > > > @@ -683,6 +683,7 @@ static int viv_read_packet(AVFormatContext *s, > > > > > > if (viv->sb_entries[viv->current_sb_entry].flag == 0) { > > > uint64_t v_size = ffio_read_varlen(pb); > > > + int last, last_start; > > > > > > if (!viv->num_audio) > > > return AVERROR_INVALIDDATA; > > > @@ -704,14 +705,22 @@ static int viv_read_packet(AVFormatContext *s, > > > start = ffio_read_varlen(pb); > > > pcm_bytes = ffio_read_varlen(pb); > > > > > > - if (i > 0 && start == 0) > > > - break; > > > + if (i > 0) { > > > + if (start == 0) > > > + break; > > > + if (start < last || start - (unsigned)last > INT_MAX) > > > > What is the second condition for? > > start is signed int so are "copyies" of it > "start < last" would allow a negative last with a large start > the 2nd check handles that. > the difference of consequtive values are stored as int later > > The patch tried to leave the storage types and check for it. > The types could be changed or some other checks could be used > I was undecided on this patch a bit too. I picked this mainly > to keep changes more minimal but maybe this was not the best > choice
Checking that start >= 0 would fix this as well, wouldn't it? I don't think it makes sense for it to be negative. -- Anton Khirnov _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
