On Tue, Sep 5, 2023 at 10:04 AM Michael Niedermayer <mich...@niedermayer.cc> wrote:
> The constraints in the specification are self contradictionary if > num_multi_layer_olss is 0 > Hi Michael, See https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/cbs_h266_syntax_template.c#L897 This loop can make sure num_multi_layer_olss > 0. The only exception is vps_ols_mode_idc == 3. which is reserved by future extension. Did you see the "ols_mode_idc == 3, patch welcome" output? Maybe we can return an error at that place. That is they require various variables to be positive and smaller than 0. So > num_multi_layer_olss cannot be 0 if vps_each_layer_is_an_ols_flag is 0 > > Its quite possible a broader check can be used, this is just the first > condition that I saw violated > > Fixes: index 257 out of bounds for type 'uint8_t [257]' > Fixes: > 61160/clusterfuzz-testcase-minimized-ffmpeg_BSF_VVC_METADATA_fuzzer-6709397181825024 > Found-by: continuous fuzzing process > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > Signed-off-by > <https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by>: > Michael Niedermayer <mich...@niedermayer.cc> > --- > libavcodec/cbs_h266_syntax_template.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/libavcodec/cbs_h266_syntax_template.c > b/libavcodec/cbs_h266_syntax_template.c > index 4075897b9a..31b9d0b030 100644 > --- a/libavcodec/cbs_h266_syntax_template.c > +++ b/libavcodec/cbs_h266_syntax_template.c > @@ -944,6 +944,10 @@ static int FUNC(vps) (CodedBitstreamContext *ctx, > RWContext *rw, > > if (!current->vps_each_layer_is_an_ols_flag) { > uint16_t vps_num_dpb_params; > + > + if (num_multi_layer_olss <= 0) > + return AVERROR_INVALIDDATA; > + > ue(vps_num_dpb_params_minus1, 0, num_multi_layer_olss - 1); > if (current->vps_each_layer_is_an_ols_flag) > vps_num_dpb_params = 0; > -- > 2.17.1 > > _______________________________________________ > 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". > _______________________________________________ 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".
