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Add clamp to prevent out of bound access

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For bad input data, the decoder may access the array out of bounds. The
commit added clamp to prevent such out of bound access

Change-Id: I0a1cfd9b8786ea7113a998053c76605c963b077a
This commit is contained in:
Yaowu Xu 2013-10-15 09:17:11 -07:00
parent 9d98e936b5
commit 45dbe94ee0
1 changed files with 4 additions and 4 deletions
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8
vp9/decoder/vp9_dsubexp.c
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@ -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) {