[FFmpeg-devel] [PATCH] avcodec/cbs_h266_syntax_template: check aps_adaptation_parameter_set_id

[Michael Niedermayer <michael@niedermayer.cc>]

From: James Almer <jamrial@gmail.com>

"When aps_params_type is equal to ALF_APS or SCALING_APS, the value of aps_adaptation_parameter_set_id shall be
in the range of 0 to 7, inclusive.
When aps_params_type is equal to LMCS_APS, the value of aps_adaptation_parameter_set_id shall be in the range of 0
to 3, inclusive."

Fixes: out of array accesses
Fixes: 65932/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VVC_fuzzer-4563412340244480

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 | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/libavcodec/cbs_h266_syntax_template.c b/libavcodec/cbs_h266_syntax_template.c
index 9e479c9c314..21da8195556 100644
--- a/libavcodec/cbs_h266_syntax_template.c
+++ b/libavcodec/cbs_h266_syntax_template.c
@@ -2457,6 +2457,7 @@ static int FUNC(scaling_list_data)(CodedBitstreamContext *ctx, RWContext *rw,
 static int FUNC(aps)(CodedBitstreamContext *ctx, RWContext *rw,
                      H266RawAPS *current, int prefix)
 {
+    int aps_id_max = MAX_UINT_BITS(5);
     int err;
 
     if (prefix)
@@ -2469,7 +2470,12 @@ static int FUNC(aps)(CodedBitstreamContext *ctx, RWContext *rw,
                                        : VVC_SUFFIX_APS_NUT));
 
     ub(3, aps_params_type);
-    ub(5, aps_adaptation_parameter_set_id);
+    if (current->aps_params_type == VVC_ASP_TYPE_ALF ||
+        current->aps_params_type == VVC_ASP_TYPE_SCALING)
+        aps_id_max = 7;
+    else if (current->aps_params_type == VVC_ASP_TYPE_LMCS)
+        aps_id_max = 3;
+    u(5, aps_adaptation_parameter_set_id, 0, aps_id_max);
     flag(aps_chroma_present_flag);
     if (current->aps_params_type == VVC_ASP_TYPE_ALF)
         CHECK(FUNC(alf_data)(ctx, rw, current));
-- 
2.17.1

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