On Tue, Jan 30, 2024 at 8:56 PM Frank Plowman <p...@frankplowman.com> wrote:
> On 30/01/2024 12:31, Nuo Mi wrote: > > > On Tue, Jan 30, 2024 at 5:41 PM<p...@frankplowman.com> wrote: > >> From: Frank Plowman<p...@frankplowman.com> > >> > >> Check that vps_each_layer_is_an_ols_flag, which indicates that "at > >> least one OLS specified by the VPS contains more than one layer," is > >> set if num_multi_layer_olss is non-zero. > >> > >> Fixes: > >> > 65160/clusterfuzz-testcase-minimized-ffmpeg_BSF_VVC_METADATA_fuzzer-4665241535119360 > >> > >> 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 > >: > >> Frank Plowman<p...@frankplowman.com> > >> --- > >> libavcodec/cbs_h266_syntax_template.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> > >> diff --git a/libavcodec/cbs_h266_syntax_template.c > >> b/libavcodec/cbs_h266_syntax_template.c > >> index 2f3478e5e1..37dc3acba0 100644 > >> --- a/libavcodec/cbs_h266_syntax_template.c > >> +++ b/libavcodec/cbs_h266_syntax_template.c > >> @@ -911,6 +911,8 @@ static int FUNC(vps) (CodedBitstreamContext *ctx, > >> RWContext *rw, > >> num_multi_layer_olss++; > >> } > >> } > >> + if (!current->vps_each_layer_is_an_ols_flag && > >> num_multi_layer_olss == 0) > >> + return AVERROR_INVALIDDATA; > >> } > > The specification does not provide information on how to obtain > > TotalNumOlss (total_num_olss) when ols_mode_idc is set to 3. > > Therefore, the earlier line "u(8, vps_num_ptls_minus1, 0, total_num_olss > - > > 1)" is undefined. > > We'd better return a patch welcome error instead of printing a warning > > before vps_num_ptls_minus1 line > > This is the same behaviour James suggested in an earlier patch. The spec > says "decoders conforming to this version of this Specification shall > ignore the OLSs with vps_ols_mode_idc equal to 3." I don't think this > should be an error as the spec is unambiguous here. Perhaps we can > instead skip the remainder of the VPS if vps_ols_mode_idc is 3? Or is > there some better way to ignore these OLSs? > Even the specification editor is uncertain about what will be included in the future. Perhaps logic later than the point needs a total rewrite. It's not an error in terms of invalid data; we simply do not know how to handle it and are asking others to provide the patch. _______________________________________________ > 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".
