h264: stricter reference limit enforcement.
authorRonald S. Bultje <rsbultje@gmail.com>
Tue, 13 Mar 2012 23:26:44 +0000 (16:26 -0700)
committerReinhard Tartler <siretart@tauware.de>
Wed, 14 Mar 2012 20:33:15 +0000 (21:33 +0100)
Progressive images can have only 16 references, error out if there are
more, since the data is almost certainly corrupt, and the invalid value
will lead to random crashes or invalid writes later on.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
(cherry picked from commit e0febda22d0e0fab094a9c886b0e0f0f662df1ef)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>
libavcodec/h264.c

index 95a672b..e0eb8e1 100644 (file)
@@ -3020,6 +3020,8 @@ static int decode_slice_header(H264Context *h, H264Context *h0){
     h->ref_count[1]= h->pps.ref_count[1];
 
     if(h->slice_type_nos != AV_PICTURE_TYPE_I){
+        int max_refs = s->picture_structure == PICT_FRAME ? 16 : 32;
+
         if(h->slice_type_nos == AV_PICTURE_TYPE_B){
             h->direct_spatial_mv_pred= get_bits1(&s->gb);
         }
@@ -3029,13 +3031,14 @@ static int decode_slice_header(H264Context *h, H264Context *h0){
             h->ref_count[0]= get_ue_golomb(&s->gb) + 1;
             if(h->slice_type_nos==AV_PICTURE_TYPE_B)
                 h->ref_count[1]= get_ue_golomb(&s->gb) + 1;
+        }
 
-            if(h->ref_count[0]-1 > 32-1 || h->ref_count[1]-1 > 32-1){
-                av_log(h->s.avctx, AV_LOG_ERROR, "reference overflow\n");
-                h->ref_count[0]= h->ref_count[1]= 1;
-                return -1;
-            }
+        if (h->ref_count[0] > max_refs || h->ref_count[1] > max_refs) {
+            av_log(h->s.avctx, AV_LOG_ERROR, "reference overflow\n");
+            h->ref_count[0] = h->ref_count[1] = 1;
+            return AVERROR_INVALIDDATA;
         }
+
         if(h->slice_type_nos == AV_PICTURE_TYPE_B)
             h->list_count= 2;
         else