On Sat, Oct 12, 2019 at 06:53:05PM -0300, James Almer wrote: > On 10/12/2019 5:47 PM, Michael Niedermayer wrote: > > On Fri, Oct 11, 2019 at 08:51:54PM +1100, Peter Ross wrote: > >> On Fri, Oct 11, 2019 at 12:40:07AM +0200, Michael Niedermayer wrote: > >>> Fixes: signed integer overflow: 1092624416 * 2 cannot be represented in > >>> type 'int' > >>> Fixes: > >>> 18045/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_BINKAUDIO_RDFT_fuzzer-5718519492116480 > >>> > >>> Found-by: continuous fuzzing process > >>> https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > >>> Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > >>> --- > >>> libavcodec/binkaudio.c | 2 ++ > >>> 1 file changed, 2 insertions(+) > >>> > >>> diff --git a/libavcodec/binkaudio.c b/libavcodec/binkaudio.c > >>> index 96cf968c66..2384ebf312 100644 > >>> --- a/libavcodec/binkaudio.c > >>> +++ b/libavcodec/binkaudio.c > >>> @@ -95,6 +95,8 @@ static av_cold int decode_init(AVCodecContext *avctx) > >>> if (avctx->codec->id == AV_CODEC_ID_BINKAUDIO_RDFT) { > >>> // audio is already interleaved for the RDFT format variant > >>> avctx->sample_fmt = AV_SAMPLE_FMT_FLT; > >>> + if (sample_rate > INT_MAX / avctx->channels) > >>> + return AVERROR_INVALIDDATA; > >>> sample_rate *= avctx->channels; > >>> s->channels = 1; > >>> if (!s->version_b) > >>> -- > >>> 2.23.0 > >> > >> i think this checl belongs inside the fuzzer test harness, or as a general > >> purpose codec check. > >> > >> the bink and smaker demuxers will only ever use BINKAUDIO_RDFT with 1 or 2 > >> channels. > > > > In the case of the overflow channels was 2 > > > > what check do you suggest to be done in general code ? > > A check specific to the fuzzer would fail to prevent this from happening > > outside the fuzzer
fair enough, approve patch. > Judging by the bink demuxer reading 16 bits for sample_rate, I assume > binkaudio has a max valid value for it, like 44k or 48k, in which case a > check like the one for channels at the beginning of this function would > be the proper non general code fix. If not one of those two values, then > just <= UINT16_MAX. the bink demuxer supplied sample_reate is 16-bits wide, smacker is 24-bits. the error can never happen when using ffmpeg+libavformat+libavcodec to play any bink or smacker files, but i guess we need to account for other use cases. -- Peter (A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
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