| Message ID | 20230905020358.32527-2-michael@niedermayer.cc |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel,1/2] avcodec/vmixdec: Fix signed integer overflow in dc | expand |
On Tue, Sep 5, 2023 at 10:04 AM Michael Niedermayer <michael@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 <michael@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-request@ffmpeg.org with subject "unsubscribe". >
On Tue, Sep 05, 2023 at 10:51:23PM +0800, Nuo Mi wrote: > On Tue, Sep 5, 2023 at 10:04 AM Michael Niedermayer <michael@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. ols_mode_idc and vps_ols_mode_idc are 2 > > 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 <michael@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-request@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-request@ffmpeg.org with subject "unsubscribe".
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;
The constraints in the specification are self contradictionary if num_multi_layer_olss is 0 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: Michael Niedermayer <michael@niedermayer.cc> --- libavcodec/cbs_h266_syntax_template.c | 4 ++++ 1 file changed, 4 insertions(+)