[FFmpeg-cvslog] avcodec/cbs_av1_syntax_template: Check num_y_points

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Wed Dec 11 22:03:50 2019 +0100| [bbe27890ff7e31e74d024a17123cb073720f2486] | committer: Michael Niedermayer

avcodec/cbs_av1_syntax_template: Check num_y_points

"It is a requirement of bitstream conformance that num_y_points is less than or equal to 14."

Fixes: index 24 out of bounds for type 'uint8_t [24]'
Fixes: 19282/clusterfuzz-testcase-minimized-ffmpeg_BSF_AV1_FRAME_MERGE_fuzzer-5747424845103104

Note, also needs a23dd33606d5

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: jamrial
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=bbe27890ff7e31e74d024a17123cb073720f2486
---

 libavcodec/cbs_av1.h                 | 4 ++--
 libavcodec/cbs_av1_syntax_template.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/libavcodec/cbs_av1.h b/libavcodec/cbs_av1.h
index 643e76793f..5466151f73 100644
--- a/libavcodec/cbs_av1.h
+++ b/libavcodec/cbs_av1.h
@@ -256,8 +256,8 @@ typedef struct AV1RawFrameHeader {
     uint8_t  update_grain;
     uint8_t  film_grain_params_ref_idx;
     uint8_t  num_y_points;
-    uint8_t  point_y_value[16];
-    uint8_t  point_y_scaling[16];
+    uint8_t  point_y_value[14];
+    uint8_t  point_y_scaling[14];
     uint8_t  chroma_scaling_from_luma;
     uint8_t  num_cb_points;
     uint8_t  point_cb_value[16];
diff --git a/libavcodec/cbs_av1_syntax_template.c b/libavcodec/cbs_av1_syntax_template.c
index f53955c52e..523f9359e4 100644
--- a/libavcodec/cbs_av1_syntax_template.c
+++ b/libavcodec/cbs_av1_syntax_template.c
@@ -1155,7 +1155,7 @@ static int FUNC(film_grain_params)(CodedBitstreamContext *ctx, RWContext *rw,
         return 0;
     }
 
-    fb(4, num_y_points);
+    fc(4, num_y_points, 0, 14);
     for (i = 0; i < current->num_y_points; i++) {
         fbs(8, point_y_value[i],   1, i);
         fbs(8, point_y_scaling[i], 1, i);