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detokenize: use SEG_LVL_EOB feature consistently

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Update decode_coefs() to break when c >= eob, since it's possible that
c starts the loop from 1 and eob is 0. The loop won't terminate in that
case.

Add new get_eob() function to consistently clamp the eob based on the
segment level EOB and the block size. It's possible to code a segment
level EOB that's greater than the block size, and that leads to an
out of bounds access.

Change-Id: I859563b30414615cf1b30dcc2aef8a1de358c42d
This commit is contained in:
John Koleszar 2012-11-14 09:51:23 -08:00 committed by Paul Wilkins
parent 5a955973d9
commit 6becad426c
2 changed files with 22 additions and 26 deletions
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2
vp9/common/seg_common.c
View File

@ -12,7 +12,7 @@
static const int segfeaturedata_signed[SEG_LVL_MAX] = { 1, 1, 0, 0, 0, 0 };
static const int seg_feature_data_bits[SEG_LVL_MAX] =
{ QINDEX_BITS, 6, 4, 5, 6, 2 };
{ QINDEX_BITS, 6, 4, 5, 8, 2 };
// These functions provide access to new segment level features.
// Eventually these function may be "optimized out" but for the moment,

46
vp9/decoder/detokenize.c
View File

@ -324,12 +324,12 @@ static int decode_coefs(VP9D_COMP *dx, const MACROBLOCKD *xd,
while (1) {
int val;
const uint8_t *cat6 = cat6_prob;
if (c == seg_eob) break;
if (c >= seg_eob) break;
prob += coef_bands[c];
if (!vp9_read(br, prob[EOB_CONTEXT_NODE]))
break;
SKIP_START:
if (c == seg_eob) break;
if (c >= seg_eob) break;
if (!vp9_read(br, prob[ZERO_CONTEXT_NODE])) {
++c;
prob = coef_probs + coef_bands[c];
@ -414,6 +414,17 @@ SKIP_START:
return c;
}
int get_eob(MACROBLOCKD* const xd, int segment_id, int eob_max) {
int active = vp9_segfeature_active(xd, segment_id, SEG_LVL_EOB);
int eob = vp9_get_segdata(xd, segment_id, SEG_LVL_EOB);
if (!active || eob > eob_max)
eob = eob_max;
return eob;
}
int vp9_decode_mb_tokens_16x16(VP9D_COMP* const pbi,
MACROBLOCKD* const xd,
BOOL_DECODER* const bc) {
@ -424,16 +435,11 @@ int vp9_decode_mb_tokens_16x16(VP9D_COMP* const pbi,
PLANE_TYPE type;
int c, i, eobtotal = 0, seg_eob;
const int segment_id = xd->mode_info_context->mbmi.segment_id;
const int seg_active = vp9_segfeature_active(xd, segment_id, SEG_LVL_EOB);
INT16 *qcoeff_ptr = &xd->qcoeff[0];
TX_TYPE tx_type = get_tx_type(xd, &xd->block[0]);
type = PLANE_TYPE_Y_WITH_DC;
if (seg_active)
seg_eob = vp9_get_segdata(xd, segment_id, SEG_LVL_EOB);
else
seg_eob = 256;
seg_eob = get_eob(xd, segment_id, 256);
// Luma block
{
@ -453,10 +459,7 @@ int vp9_decode_mb_tokens_16x16(VP9D_COMP* const pbi,
qcoeff_ptr += 256;
type = PLANE_TYPE_UV;
tx_type = DCT_DCT;
if (seg_active)
seg_eob = vp9_get_segdata(xd, segment_id, SEG_LVL_EOB);
else
seg_eob = 64;
seg_eob = get_eob(xd, segment_id, 64);
for (i = 16; i < 24; i += 4) {
ENTROPY_CONTEXT* const a = A + vp9_block2above_8x8[i];
ENTROPY_CONTEXT* const l = L + vp9_block2left_8x8[i];
@ -488,7 +491,6 @@ int vp9_decode_mb_tokens_8x8(VP9D_COMP* const pbi,
PLANE_TYPE type;
int c, i, eobtotal = 0, seg_eob;
const int segment_id = xd->mode_info_context->mbmi.segment_id;
const int seg_active = vp9_segfeature_active(xd, segment_id, SEG_LVL_EOB);
INT16 *qcoeff_ptr = &xd->qcoeff[0];
TX_TYPE tx_type = DCT_DCT;
@ -502,10 +504,7 @@ int vp9_decode_mb_tokens_8x8(VP9D_COMP* const pbi,
const int *const scan = vp9_default_zig_zag1d;
type = PLANE_TYPE_Y2;
if (seg_active)
seg_eob = vp9_get_segdata(xd, segment_id, SEG_LVL_EOB);
else
seg_eob = 4;
seg_eob = get_eob(xd, segment_id, 4);
c = decode_coefs(pbi, xd, bc, a, l, type,
tx_type,
seg_eob, qcoeff_ptr + 24 * 16,
@ -518,10 +517,7 @@ int vp9_decode_mb_tokens_8x8(VP9D_COMP* const pbi,
} else
type = PLANE_TYPE_Y_WITH_DC;
if (seg_active)
seg_eob = vp9_get_segdata(xd, segment_id, SEG_LVL_EOB);
else
seg_eob = 64;
seg_eob = get_eob(xd, segment_id, 64);
for (i = 0; i < bufthred ; i += 4) {
ENTROPY_CONTEXT *const a = A + vp9_block2above_8x8[i];
@ -550,7 +546,7 @@ int vp9_decode_mb_tokens_8x8(VP9D_COMP* const pbi,
if (bufthred == 16) {
type = PLANE_TYPE_UV;
tx_type = DCT_DCT;
seg_eob = 16;
seg_eob = get_eob(xd, segment_id, 16);
// use 4x4 transform for U, V components in I8X8 prediction mode
for (i = 16; i < 24; i++) {
@ -581,11 +577,11 @@ int vp9_decode_coefs_4x4(VP9D_COMP *dx, MACROBLOCKD *xd,
INT16 *qcoeff_ptr = &xd->qcoeff[0];
const int *scan = vp9_default_zig_zag1d;
unsigned short *const eobs = xd->eobs;
int c, seg_eob = 16;
int c, seg_eob;
TX_TYPE tx_type = DCT_DCT;
int segment_id = xd->mode_info_context->mbmi.segment_id;
if (vp9_segfeature_active(xd, segment_id, SEG_LVL_EOB))
seg_eob = vp9_get_segdata(xd, segment_id, SEG_LVL_EOB);
seg_eob = get_eob(xd, segment_id, 16);
if (i == 24)
type = PLANE_TYPE_Y2;