Re: [FFmpeg-devel] [PATCH] avcodec/hevc_ps: add proper bound checks around cm_ref_layer_id in colour_mapping_table.

[James Almer]

On 5/17/2023 2:28 PM, Michael Niedermayer wrote:

From: Clement Lecigne <cleci...@google.com>

Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
---
  libavcodec/hevc_ps.c | 17 +++++++++++++----
  1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/libavcodec/hevc_ps.c b/libavcodec/hevc_ps.c
index a55bced0f7..313ebef151 100644
--- a/libavcodec/hevc_ps.c
+++ b/libavcodec/hevc_ps.c
@@ -1374,9 +1374,14 @@ static void colour_mapping_octants(GetBitContext *gb, 
HEVCPPS *pps, int inp_dept
          }
  }

-static void colour_mapping_table(GetBitContext *gb, HEVCPPS *pps)

+static int colour_mapping_table(GetBitContext *gb, AVCodecContext *avctx, 
HEVCPPS *pps)
  {
-    pps->num_cm_ref_layers_minus1 = get_ue_golomb_long(gb);
+    pps->num_cm_ref_layers_minus1 = get_ue_golomb(gb);
+    if (pps->num_cm_ref_layers_minus1 >= 63U) {
+        av_log(avctx, AV_LOG_ERROR,
+               "num_cm_ref_layers_minus1 shall be in the range [0, 63].\n");

The spec in section F.7.4.3.3.5 says 0..61, no 0..63.

I'll amend this (and update the array in the struct while at it) and push.

+        return AVERROR_INVALIDDATA;
+    }
      for (int i = 0; i <= pps->num_cm_ref_layers_minus1; i++)
          pps->cm_ref_layer_id[i] = get_bits(gb, 6);

@@ -1397,6 +1402,7 @@ static void colour_mapping_table(GetBitContext *gb, HEVCPPS *pps)

      }

colour_mapping_octants(gb, pps, 0, 0, 0, 0, 1 << pps->cm_octant_depth);

+    return 0;
  }

static int pps_multilayer_extension(GetBitContext *gb, AVCodecContext *avctx,

@@ -1439,8 +1445,11 @@ static int pps_multilayer_extension(GetBitContext *gb, 
AVCodecContext *avctx,
      }

pps->colour_mapping_enabled_flag = get_bits1(gb);

-    if (pps->colour_mapping_enabled_flag)
-        colour_mapping_table(gb, pps);
+    if (pps->colour_mapping_enabled_flag) {
+        int ret = colour_mapping_table(gb, avctx, pps);
+        if (ret < 0)
+            return ret;
+    }

return 0;

  }

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