[FFmpeg-cvslog] mpeg12: check scantable indices in all decode_block functions
Janne Grunau
git at videolan.org
Sun Jan 26 03:18:11 CET 2014
ffmpeg | branch: master | Janne Grunau <janne-libav at jannau.net> | Fri Jan 24 16:22:44 2014 +0100| [6d93307f8df81808f0dcdbc064b848054a6e83b3] | committer: Janne Grunau
mpeg12: check scantable indices in all decode_block functions
Add checks to the fast functions used with CODEC_FLAGS2_FAST and move
the check for all other functions to before the invalid memory is
accessed. Fixes https://trac.videolan.org/vlc/ticket/9713 with
CODEC_FLAGS2_FAST.
CC: libav-stable at libav.org
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=6d93307f8df81808f0dcdbc064b848054a6e83b3
---
libavcodec/mpeg12dec.c | 54 +++++++++++++++++++++++++++---------------------
1 file changed, 31 insertions(+), 23 deletions(-)
diff --git a/libavcodec/mpeg12dec.c b/libavcodec/mpeg12dec.c
index 49b7d1e..f0e390d 100644
--- a/libavcodec/mpeg12dec.c
+++ b/libavcodec/mpeg12dec.c
@@ -119,6 +119,15 @@ static int mpeg_decode_motion(MpegEncContext *s, int fcode, int pred)
return sign_extend(val, 5 + shift);
}
+#define check_scantable_index(ctx, x) \
+ do { \
+ if ((x) > 63) { \
+ av_log(ctx->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", \
+ ctx->mb_x, ctx->mb_y); \
+ return AVERROR_INVALIDDATA; \
+ } \
+ } while (0) \
+
static inline int mpeg1_decode_block_intra(MpegEncContext *s, int16_t *block, int n)
{
int level, dc, diff, i, j, run;
@@ -150,6 +159,7 @@ static inline int mpeg1_decode_block_intra(MpegEncContext *s, int16_t *block, in
break;
} else if (level != 0) {
i += run;
+ check_scantable_index(s, i);
j = scantable[i];
level = (level * qscale * quant_matrix[j]) >> 4;
level = (level - 1) | 1;
@@ -166,6 +176,7 @@ static inline int mpeg1_decode_block_intra(MpegEncContext *s, int16_t *block, in
level = SHOW_UBITS(re, &s->gb, 8) ; LAST_SKIP_BITS(re, &s->gb, 8);
}
i += run;
+ check_scantable_index(s, i);
j = scantable[i];
if (level < 0) {
level = -level;
@@ -177,10 +188,6 @@ static inline int mpeg1_decode_block_intra(MpegEncContext *s, int16_t *block, in
level = (level - 1) | 1;
}
}
- if (i > 63) {
- av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
- return -1;
- }
block[j] = level;
}
@@ -225,6 +232,7 @@ static inline int mpeg1_decode_block_inter(MpegEncContext *s, int16_t *block, in
if (level != 0) {
i += run;
+ check_scantable_index(s, i);
j = scantable[i];
level = ((level * 2 + 1) * qscale * quant_matrix[j]) >> 5;
level = (level - 1) | 1;
@@ -241,6 +249,7 @@ static inline int mpeg1_decode_block_inter(MpegEncContext *s, int16_t *block, in
level = SHOW_UBITS(re, &s->gb, 8) ; SKIP_BITS(re, &s->gb, 8);
}
i += run;
+ check_scantable_index(s, i);
j = scantable[i];
if (level < 0) {
level = -level;
@@ -252,10 +261,6 @@ static inline int mpeg1_decode_block_inter(MpegEncContext *s, int16_t *block, in
level = (level - 1) | 1;
}
}
- if (i > 63) {
- av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
- return -1;
- }
block[j] = level;
if (((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF)
@@ -300,6 +305,7 @@ static inline int mpeg1_fast_decode_block_inter(MpegEncContext *s, int16_t *bloc
if (level != 0) {
i += run;
+ check_scantable_index(s, i);
j = scantable[i];
level = ((level * 2 + 1) * qscale) >> 1;
level = (level - 1) | 1;
@@ -316,6 +322,7 @@ static inline int mpeg1_fast_decode_block_inter(MpegEncContext *s, int16_t *bloc
level = SHOW_UBITS(re, &s->gb, 8) ; SKIP_BITS(re, &s->gb, 8);
}
i += run;
+ check_scantable_index(s, i);
j = scantable[i];
if (level < 0) {
level = -level;
@@ -381,6 +388,7 @@ static inline int mpeg2_decode_block_non_intra(MpegEncContext *s, int16_t *block
if (level != 0) {
i += run;
+ check_scantable_index(s, i);
j = scantable[i];
level = ((level * 2 + 1) * qscale * quant_matrix[j]) >> 5;
level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
@@ -392,6 +400,7 @@ static inline int mpeg2_decode_block_non_intra(MpegEncContext *s, int16_t *block
level = SHOW_SBITS(re, &s->gb, 12); SKIP_BITS(re, &s->gb, 12);
i += run;
+ check_scantable_index(s, i);
j = scantable[i];
if (level < 0) {
level = ((-level * 2 + 1) * qscale * quant_matrix[j]) >> 5;
@@ -400,10 +409,6 @@ static inline int mpeg2_decode_block_non_intra(MpegEncContext *s, int16_t *block
level = ((level * 2 + 1) * qscale * quant_matrix[j]) >> 5;
}
}
- if (i > 63) {
- av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
- return -1;
- }
mismatch ^= level;
block[j] = level;
@@ -450,6 +455,7 @@ static inline int mpeg2_fast_decode_block_non_intra(MpegEncContext *s,
if (level != 0) {
i += run;
+ check_scantable_index(s, i);
j = scantable[i];
level = ((level * 2 + 1) * qscale) >> 1;
level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
@@ -461,6 +467,7 @@ static inline int mpeg2_fast_decode_block_non_intra(MpegEncContext *s,
level = SHOW_SBITS(re, &s->gb, 12); SKIP_BITS(re, &s->gb, 12);
i += run;
+ check_scantable_index(s, i);
j = scantable[i];
if (level < 0) {
level = ((-level * 2 + 1) * qscale) >> 1;
@@ -527,6 +534,7 @@ static inline int mpeg2_decode_block_intra(MpegEncContext *s, int16_t *block, in
break;
} else if (level != 0) {
i += run;
+ check_scantable_index(s, i);
j = scantable[i];
level = (level * qscale * quant_matrix[j]) >> 4;
level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
@@ -537,6 +545,7 @@ static inline int mpeg2_decode_block_intra(MpegEncContext *s, int16_t *block, in
UPDATE_CACHE(re, &s->gb);
level = SHOW_SBITS(re, &s->gb, 12); SKIP_BITS(re, &s->gb, 12);
i += run;
+ check_scantable_index(s, i);
j = scantable[i];
if (level < 0) {
level = (-level * qscale * quant_matrix[j]) >> 4;
@@ -545,10 +554,6 @@ static inline int mpeg2_decode_block_intra(MpegEncContext *s, int16_t *block, in
level = (level * qscale * quant_matrix[j]) >> 4;
}
}
- if (i > 63) {
- av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
- return -1;
- }
mismatch ^= level;
block[j] = level;
@@ -563,10 +568,10 @@ static inline int mpeg2_decode_block_intra(MpegEncContext *s, int16_t *block, in
static inline int mpeg2_fast_decode_block_intra(MpegEncContext *s, int16_t *block, int n)
{
- int level, dc, diff, j, run;
+ int level, dc, diff, i, j, run;
int component;
RLTable *rl;
- uint8_t * scantable = s->intra_scantable.permutated;
+ uint8_t * const scantable = s->intra_scantable.permutated;
const uint16_t *quant_matrix;
const int qscale = s->qscale;
@@ -585,6 +590,7 @@ static inline int mpeg2_fast_decode_block_intra(MpegEncContext *s, int16_t *bloc
dc += diff;
s->last_dc[component] = dc;
block[0] = dc << (3 - s->intra_dc_precision);
+ i = 0;
if (s->intra_vlc_format)
rl = &ff_rl_mpeg2;
else
@@ -600,8 +606,9 @@ static inline int mpeg2_fast_decode_block_intra(MpegEncContext *s, int16_t *bloc
if (level == 127) {
break;
} else if (level != 0) {
- scantable += run;
- j = *scantable;
+ i += run;
+ check_scantable_index(s, i);
+ j = scantable[i];
level = (level * qscale * quant_matrix[j]) >> 4;
level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
LAST_SKIP_BITS(re, &s->gb, 1);
@@ -610,8 +617,9 @@ static inline int mpeg2_fast_decode_block_intra(MpegEncContext *s, int16_t *bloc
run = SHOW_UBITS(re, &s->gb, 6) + 1; LAST_SKIP_BITS(re, &s->gb, 6);
UPDATE_CACHE(re, &s->gb);
level = SHOW_SBITS(re, &s->gb, 12); SKIP_BITS(re, &s->gb, 12);
- scantable += run;
- j = *scantable;
+ i += run;
+ check_scantable_index(s, i);
+ j = scantable[i];
if (level < 0) {
level = (-level * qscale * quant_matrix[j]) >> 4;
level = -level;
@@ -625,7 +633,7 @@ static inline int mpeg2_fast_decode_block_intra(MpegEncContext *s, int16_t *bloc
CLOSE_READER(re, &s->gb);
}
- s->block_last_index[n] = scantable - s->intra_scantable.permutated;
+ s->block_last_index[n] = i;
return 0;
}
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