From 6d93307f8df81808f0dcdbc064b848054a6e83b3 Mon Sep 17 00:00:00 2001 From: Janne Grunau Date: Fri, 24 Jan 2014 16:22:44 +0100 Subject: [PATCH] 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@libav.org --- libavcodec/mpeg12dec.c | 54 +++++++++++++++++++++++++++++--------------------- 1 file changed, 31 insertions(+), 23 deletions(-) diff --git a/libavcodec/mpeg12dec.c b/libavcodec/mpeg12dec.c index 49b7d1e65c..f0e390d790 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; } -- 2.11.0