| Message ID | 20201114101815.24489-1-michael@niedermayer.cc |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel,1/2] avcodec/cbs_h265_syntax_template: Better check for num_long_term_sps | expand |
| Context | Check | Description |
|---|---|---|
| andriy/x86_make | success | Make finished |
| andriy/x86_make_fate | success | Make fate finished |
On 14/11/2020 10:18, Michael Niedermayer wrote: > Fixes: index 26 out of bounds for type 'uint8_t [16]' > Fixes: 24913/clusterfuzz-testcase-minimized-ffmpeg_BSF_HEVC_METADATA_fuzzer-6261760693370880 > > 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_h265_syntax_template.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/libavcodec/cbs_h265_syntax_template.c b/libavcodec/cbs_h265_syntax_template.c > index 48fae82d04..8eb6e159f4 100644 > --- a/libavcodec/cbs_h265_syntax_template.c > +++ b/libavcodec/cbs_h265_syntax_template.c > @@ -1405,6 +1405,8 @@ static int FUNC(slice_segment_header)(CodedBitstreamContext *ctx, RWContext *rw, > infer(num_long_term_sps, 0); > idx_size = 0; > } > + if (HEVC_MAX_REFS < current->num_long_term_sps) > + return AVERROR_INVALIDDATA; Please don't put isolated tests in the middle of the template. If it constrains a value then add it to the constraints on that value. > ue(num_long_term_pics, 0, HEVC_MAX_REFS - current->num_long_term_sps); > > for (i = 0; i < current->num_long_term_sps + > It would be good if the commit message could include an explanation derived from the standard, too. As far as I can tell the constraint doesn't appear explicitly, but the SPS is allowed to define more possible long term frames than are actually allowed to be present at any given moment so we need the tighter bound. - Mark
On Sun, Nov 15, 2020 at 09:37:45PM +0000, Mark Thompson wrote: > On 14/11/2020 10:18, Michael Niedermayer wrote: > > Fixes: index 26 out of bounds for type 'uint8_t [16]' > > Fixes: 24913/clusterfuzz-testcase-minimized-ffmpeg_BSF_HEVC_METADATA_fuzzer-6261760693370880 > > > > 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_h265_syntax_template.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/libavcodec/cbs_h265_syntax_template.c b/libavcodec/cbs_h265_syntax_template.c > > index 48fae82d04..8eb6e159f4 100644 > > --- a/libavcodec/cbs_h265_syntax_template.c > > +++ b/libavcodec/cbs_h265_syntax_template.c > > @@ -1405,6 +1405,8 @@ static int FUNC(slice_segment_header)(CodedBitstreamContext *ctx, RWContext *rw, > > infer(num_long_term_sps, 0); > > idx_size = 0; > > } > > + if (HEVC_MAX_REFS < current->num_long_term_sps) > > + return AVERROR_INVALIDDATA; > > Please don't put isolated tests in the middle of the template. If it constrains a value then add it to the constraints on that value. > > > ue(num_long_term_pics, 0, HEVC_MAX_REFS - current->num_long_term_sps); > > for (i = 0; i < current->num_long_term_sps + > > > > It would be good if the commit message could include an explanation derived from the standard, too. > > As far as I can tell the constraint doesn't appear explicitly, but the SPS is allowed to define more possible long term frames than are actually allowed to be present at any given moment so we need the tighter bound. Is the change below what you had in mind ? commit 72c6c46bb2b31b2822331aff461acccd0a4f9159 (HEAD -> master) Author: Michael Niedermayer <michael@niedermayer.cc> Date: Fri Nov 13 23:15:52 2020 +0100 avcodec/cbs_h265_syntax_template: Better check for num_long_term_sps As far as we can tell the constraint doesn't appear explicitly, but the SPS is allowed to define more possible long term frames than are actually allowed to be present at any given moment so we need the tighter bound. Fixes: index 26 out of bounds for type 'uint8_t [16]' Fixes: 24913/clusterfuzz-testcase-minimized-ffmpeg_BSF_HEVC_METADATA_fuzzer-6261760693370880 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> diff --git a/libavcodec/cbs_h265_syntax_template.c b/libavcodec/cbs_h265_syntax_template.c index 48fae82d04..30f2bd328c 100644 --- a/libavcodec/cbs_h265_syntax_template.c +++ b/libavcodec/cbs_h265_syntax_template.c @@ -1399,7 +1399,7 @@ static int FUNC(slice_segment_header)(CodedBitstreamContext *ctx, RWContext *rw, unsigned int idx_size; if (sps->num_long_term_ref_pics_sps > 0) { - ue(num_long_term_sps, 0, sps->num_long_term_ref_pics_sps); + ue(num_long_term_sps, 0, FFMIN(sps->num_long_term_ref_pics_sps, HEVC_MAX_REFS)); idx_size = av_log2(sps->num_long_term_ref_pics_sps - 1) + 1; } else { infer(num_long_term_sps, 0); [...]
On 21/11/2020 17:37, Michael Niedermayer wrote: > On Sun, Nov 15, 2020 at 09:37:45PM +0000, Mark Thompson wrote: >> On 14/11/2020 10:18, Michael Niedermayer wrote: >>> Fixes: index 26 out of bounds for type 'uint8_t [16]' >>> Fixes: 24913/clusterfuzz-testcase-minimized-ffmpeg_BSF_HEVC_METADATA_fuzzer-6261760693370880 >>> >>> 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_h265_syntax_template.c | 2 ++ >>> 1 file changed, 2 insertions(+) >>> >>> diff --git a/libavcodec/cbs_h265_syntax_template.c b/libavcodec/cbs_h265_syntax_template.c >>> index 48fae82d04..8eb6e159f4 100644 >>> --- a/libavcodec/cbs_h265_syntax_template.c >>> +++ b/libavcodec/cbs_h265_syntax_template.c >>> @@ -1405,6 +1405,8 @@ static int FUNC(slice_segment_header)(CodedBitstreamContext *ctx, RWContext *rw, >>> infer(num_long_term_sps, 0); >>> idx_size = 0; >>> } >>> + if (HEVC_MAX_REFS < current->num_long_term_sps) >>> + return AVERROR_INVALIDDATA; >> >> Please don't put isolated tests in the middle of the template. If it constrains a value then add it to the constraints on that value. >> >>> ue(num_long_term_pics, 0, HEVC_MAX_REFS - current->num_long_term_sps); >>> for (i = 0; i < current->num_long_term_sps + >>> >> >> It would be good if the commit message could include an explanation derived from the standard, too. >> >> As far as I can tell the constraint doesn't appear explicitly, but the SPS is allowed to define more possible long term frames than are actually allowed to be present at any given moment so we need the tighter bound. > > Is the change below what you had in mind ? > > commit 72c6c46bb2b31b2822331aff461acccd0a4f9159 (HEAD -> master) > Author: Michael Niedermayer <michael@niedermayer.cc> > Date: Fri Nov 13 23:15:52 2020 +0100 > > avcodec/cbs_h265_syntax_template: Better check for num_long_term_sps > > As far as we can tell the constraint doesn't appear explicitly, but the SPS is allowed to > define more possible long term frames than are actually allowed to be present at any given moment so we need the tighter bound. I meant write a commit message which explains where in the standard the constraint is coming from. I wrote that because I didn't see any extra constraint written in the standard for num_long_term_sps but num_long_term_ref_pics_sps is indeed bigger, so presumably it must be implied by something else. > > Fixes: index 26 out of bounds for type 'uint8_t [16]' > Fixes: 24913/clusterfuzz-testcase-minimized-ffmpeg_BSF_HEVC_METADATA_fuzzer-6261760693370880 > > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> > > diff --git a/libavcodec/cbs_h265_syntax_template.c b/libavcodec/cbs_h265_syntax_template.c > index 48fae82d04..30f2bd328c 100644 > --- a/libavcodec/cbs_h265_syntax_template.c > +++ b/libavcodec/cbs_h265_syntax_template.c > @@ -1399,7 +1399,7 @@ static int FUNC(slice_segment_header)(CodedBitstreamContext *ctx, RWContext *rw, > unsigned int idx_size; > > if (sps->num_long_term_ref_pics_sps > 0) { > - ue(num_long_term_sps, 0, sps->num_long_term_ref_pics_sps); > + ue(num_long_term_sps, 0, FFMIN(sps->num_long_term_ref_pics_sps, HEVC_MAX_REFS)); Yes to this part. > idx_size = av_log2(sps->num_long_term_ref_pics_sps - 1) + 1; > } else { > infer(num_long_term_sps, 0); > > [...] - Mark
On Sat, Nov 21, 2020 at 06:49:55PM +0000, Mark Thompson wrote: > On 21/11/2020 17:37, Michael Niedermayer wrote: > > On Sun, Nov 15, 2020 at 09:37:45PM +0000, Mark Thompson wrote: > > > On 14/11/2020 10:18, Michael Niedermayer wrote: > > > > Fixes: index 26 out of bounds for type 'uint8_t [16]' > > > > Fixes: 24913/clusterfuzz-testcase-minimized-ffmpeg_BSF_HEVC_METADATA_fuzzer-6261760693370880 > > > > > > > > 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_h265_syntax_template.c | 2 ++ > > > > 1 file changed, 2 insertions(+) > > > > > > > > diff --git a/libavcodec/cbs_h265_syntax_template.c b/libavcodec/cbs_h265_syntax_template.c > > > > index 48fae82d04..8eb6e159f4 100644 > > > > --- a/libavcodec/cbs_h265_syntax_template.c > > > > +++ b/libavcodec/cbs_h265_syntax_template.c > > > > @@ -1405,6 +1405,8 @@ static int FUNC(slice_segment_header)(CodedBitstreamContext *ctx, RWContext *rw, > > > > infer(num_long_term_sps, 0); > > > > idx_size = 0; > > > > } > > > > + if (HEVC_MAX_REFS < current->num_long_term_sps) > > > > + return AVERROR_INVALIDDATA; > > > > > > Please don't put isolated tests in the middle of the template. If it constrains a value then add it to the constraints on that value. > > > > > > > ue(num_long_term_pics, 0, HEVC_MAX_REFS - current->num_long_term_sps); > > > > for (i = 0; i < current->num_long_term_sps + > > > > > > > > > > It would be good if the commit message could include an explanation derived from the standard, too. > > > > > > As far as I can tell the constraint doesn't appear explicitly, but the SPS is allowed to define more possible long term frames than are actually allowed to be present at any given moment so we need the tighter bound. > > > > Is the change below what you had in mind ? > > > > commit 72c6c46bb2b31b2822331aff461acccd0a4f9159 (HEAD -> master) > > Author: Michael Niedermayer <michael@niedermayer.cc> > > Date: Fri Nov 13 23:15:52 2020 +0100 > > > > avcodec/cbs_h265_syntax_template: Better check for num_long_term_sps > > As far as we can tell the constraint doesn't appear explicitly, but the SPS is allowed to > > define more possible long term frames than are actually allowed to be present at any given moment so we need the tighter bound. > > I meant write a commit message which explains where in the standard the constraint is coming from. I wrote that because I didn't see any extra constraint written in the standard for num_long_term_sps but num_long_term_ref_pics_sps is indeed bigger, so presumably it must be implied by something else. what do you suggest if noone finds that "something else" ? thx [...]
On 24/01/2021 21:41, Michael Niedermayer wrote: > On Sat, Nov 21, 2020 at 06:49:55PM +0000, Mark Thompson wrote: >> On 21/11/2020 17:37, Michael Niedermayer wrote: >>> On Sun, Nov 15, 2020 at 09:37:45PM +0000, Mark Thompson wrote: >>>> On 14/11/2020 10:18, Michael Niedermayer wrote: >>>>> Fixes: index 26 out of bounds for type 'uint8_t [16]' >>>>> Fixes: 24913/clusterfuzz-testcase-minimized-ffmpeg_BSF_HEVC_METADATA_fuzzer-6261760693370880 >>>>> >>>>> 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_h265_syntax_template.c | 2 ++ >>>>> 1 file changed, 2 insertions(+) >>>>> >>>>> diff --git a/libavcodec/cbs_h265_syntax_template.c b/libavcodec/cbs_h265_syntax_template.c >>>>> index 48fae82d04..8eb6e159f4 100644 >>>>> --- a/libavcodec/cbs_h265_syntax_template.c >>>>> +++ b/libavcodec/cbs_h265_syntax_template.c >>>>> @@ -1405,6 +1405,8 @@ static int FUNC(slice_segment_header)(CodedBitstreamContext *ctx, RWContext *rw, >>>>> infer(num_long_term_sps, 0); >>>>> idx_size = 0; >>>>> } >>>>> + if (HEVC_MAX_REFS < current->num_long_term_sps) >>>>> + return AVERROR_INVALIDDATA; >>>> >>>> Please don't put isolated tests in the middle of the template. If it constrains a value then add it to the constraints on that value. >>>> >>>>> ue(num_long_term_pics, 0, HEVC_MAX_REFS - current->num_long_term_sps); >>>>> for (i = 0; i < current->num_long_term_sps + >>>>> >>>> >>>> It would be good if the commit message could include an explanation derived from the standard, too. >>>> >>>> As far as I can tell the constraint doesn't appear explicitly, but the SPS is allowed to define more possible long term frames than are actually allowed to be present at any given moment so we need the tighter bound. >>> >>> Is the change below what you had in mind ? >>> >>> commit 72c6c46bb2b31b2822331aff461acccd0a4f9159 (HEAD -> master) >>> Author: Michael Niedermayer <michael@niedermayer.cc> >>> Date: Fri Nov 13 23:15:52 2020 +0100 >>> >>> avcodec/cbs_h265_syntax_template: Better check for num_long_term_sps >>> As far as we can tell the constraint doesn't appear explicitly, but the SPS is allowed to >>> define more possible long term frames than are actually allowed to be present at any given moment so we need the tighter bound. >> >> I meant write a commit message which explains where in the standard the constraint is coming from. I wrote that because I didn't see any extra constraint written in the standard for num_long_term_sps but num_long_term_ref_pics_sps is indeed bigger, so presumably it must be implied by something else. > > what do you suggest if noone finds that "something else" ? If you have given up on this then I would try to work out what is going on here myself? - Mark
On Mon, Jan 25, 2021 at 08:36:59PM +0000, Mark Thompson wrote: > On 24/01/2021 21:41, Michael Niedermayer wrote: > > On Sat, Nov 21, 2020 at 06:49:55PM +0000, Mark Thompson wrote: > > > On 21/11/2020 17:37, Michael Niedermayer wrote: > > > > On Sun, Nov 15, 2020 at 09:37:45PM +0000, Mark Thompson wrote: > > > > > On 14/11/2020 10:18, Michael Niedermayer wrote: > > > > > > Fixes: index 26 out of bounds for type 'uint8_t [16]' > > > > > > Fixes: 24913/clusterfuzz-testcase-minimized-ffmpeg_BSF_HEVC_METADATA_fuzzer-6261760693370880 > > > > > > > > > > > > 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_h265_syntax_template.c | 2 ++ > > > > > > 1 file changed, 2 insertions(+) > > > > > > > > > > > > diff --git a/libavcodec/cbs_h265_syntax_template.c b/libavcodec/cbs_h265_syntax_template.c > > > > > > index 48fae82d04..8eb6e159f4 100644 > > > > > > --- a/libavcodec/cbs_h265_syntax_template.c > > > > > > +++ b/libavcodec/cbs_h265_syntax_template.c > > > > > > @@ -1405,6 +1405,8 @@ static int FUNC(slice_segment_header)(CodedBitstreamContext *ctx, RWContext *rw, > > > > > > infer(num_long_term_sps, 0); > > > > > > idx_size = 0; > > > > > > } > > > > > > + if (HEVC_MAX_REFS < current->num_long_term_sps) > > > > > > + return AVERROR_INVALIDDATA; > > > > > > > > > > Please don't put isolated tests in the middle of the template. If it constrains a value then add it to the constraints on that value. > > > > > > > > > > > ue(num_long_term_pics, 0, HEVC_MAX_REFS - current->num_long_term_sps); > > > > > > for (i = 0; i < current->num_long_term_sps + > > > > > > > > > > > > > > > > It would be good if the commit message could include an explanation derived from the standard, too. > > > > > > > > > > As far as I can tell the constraint doesn't appear explicitly, but the SPS is allowed to define more possible long term frames than are actually allowed to be present at any given moment so we need the tighter bound. > > > > > > > > Is the change below what you had in mind ? > > > > > > > > commit 72c6c46bb2b31b2822331aff461acccd0a4f9159 (HEAD -> master) > > > > Author: Michael Niedermayer <michael@niedermayer.cc> > > > > Date: Fri Nov 13 23:15:52 2020 +0100 > > > > > > > > avcodec/cbs_h265_syntax_template: Better check for num_long_term_sps > > > > As far as we can tell the constraint doesn't appear explicitly, but the SPS is allowed to > > > > define more possible long term frames than are actually allowed to be present at any given moment so we need the tighter bound. > > > > > > I meant write a commit message which explains where in the standard the constraint is coming from. I wrote that because I didn't see any extra constraint written in the standard for num_long_term_sps but num_long_term_ref_pics_sps is indeed bigger, so presumably it must be implied by something else. > > > > what do you suggest if noone finds that "something else" ? > > If you have given up on this then I would try to work out what is going on here myself? "given up" is inprecisse, its more a mix between hoping that someone who knows hevc very well would just look at this and know and that without knowing its potentially quite a bit of work and the fix seemed important but the argumentation why exactly we arent allowed to access outside the array and why its fixed one way and not another seemed more or less detail. Thats in light of having other lower hanging fruits to work on ... So yes if you want to investigate, you can go right ahead Thanks [...]
diff --git a/libavcodec/cbs_h265_syntax_template.c b/libavcodec/cbs_h265_syntax_template.c index 48fae82d04..8eb6e159f4 100644 --- a/libavcodec/cbs_h265_syntax_template.c +++ b/libavcodec/cbs_h265_syntax_template.c @@ -1405,6 +1405,8 @@ static int FUNC(slice_segment_header)(CodedBitstreamContext *ctx, RWContext *rw, infer(num_long_term_sps, 0); idx_size = 0; } + if (HEVC_MAX_REFS < current->num_long_term_sps) + return AVERROR_INVALIDDATA; ue(num_long_term_pics, 0, HEVC_MAX_REFS - current->num_long_term_sps); for (i = 0; i < current->num_long_term_sps +
Fixes: index 26 out of bounds for type 'uint8_t [16]' Fixes: 24913/clusterfuzz-testcase-minimized-ffmpeg_BSF_HEVC_METADATA_fuzzer-6261760693370880 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_h265_syntax_template.c | 2 ++ 1 file changed, 2 insertions(+)