Merge "Add clamp to prevent out of bound access"

vp9/decoder/vp9_dsubexp.c

@@ -48,8 +48,6 @@ static int merge_index(int v, int n, int modulus) {
 
 static int inv_remap_prob(int v, int m) {
   static int inv_map_table[MAX_PROB - 1] = {
-    // generated by:
-    //   inv_map_table[j] = merge_index(j, MAX_PROB - 1, MODULUS_PARAM);
       6,  19,  32,  45,  58,  71,  84,  97, 110, 123, 136, 149, 162, 175, 188,
     201, 214, 227, 240, 253,   0,   1,   2,   3,   4,   5,   7,   8,   9,  10,
      11,  12,  13,  14,  15,  16,  17,  18,  20,  21,  22,  23,  24,  25,  26,
@@ -66,9 +64,11 @@ static int inv_remap_prob(int v, int m) {
     190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 202, 203, 204, 205,
     206, 207, 208, 209, 210, 211, 212, 213, 215, 216, 217, 218, 219, 220, 221,
     222, 223, 224, 225, 226, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237,
-    238, 239, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252,
+    238, 239, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252
   };
-  // v = merge_index(v, MAX_PROBS - 1, MODULUS_PARAM);
+  // The clamp is not necessary for conforming VP9 stream, it is added to
+  // prevent out of bound access for bad input data
+  v = clamp(v, 0, 253);
   v = inv_map_table[v];
   m--;
   if ((m << 1) <= MAX_PROB) {