From 9243ec4a508c81a621e941bb7e012e2d45d93659 Mon Sep 17 00:00:00 2001 From: Alex Converse Date: Thu, 1 Mar 2012 13:24:55 -0800 Subject: [PATCH] rv10/20: Fix slice overflow with checked bitstream reader. --- libavcodec/rv10.c | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) diff --git a/libavcodec/rv10.c b/libavcodec/rv10.c index 5dd08e9..2b1a09d 100644 --- a/libavcodec/rv10.c +++ b/libavcodec/rv10.c @@ -499,9 +499,10 @@ static int rv10_decode_packet(AVCodecContext *avctx, const uint8_t *buf, int buf_size, int buf_size2) { MpegEncContext *s = avctx->priv_data; - int mb_count, mb_pos, left, start_mb_x; + int mb_count, mb_pos, left, start_mb_x, active_bits_size; - init_get_bits(&s->gb, buf, buf_size*8); + active_bits_size = buf_size * 8; + init_get_bits(&s->gb, buf, FFMAX(buf_size, buf_size2) * 8); if(s->codec_id ==CODEC_ID_RV10) mb_count = rv10_decode_picture_header(s); else @@ -584,13 +585,26 @@ static int rv10_decode_packet(AVCodecContext *avctx, s->mv_type = MV_TYPE_16X16; ret=ff_h263_decode_mb(s, s->block); - if (ret != SLICE_ERROR && s->gb.size_in_bits < get_bits_count(&s->gb) && 8*buf_size2 >= get_bits_count(&s->gb)){ - av_log(avctx, AV_LOG_DEBUG, "update size from %d to %d\n", s->gb.size_in_bits, 8*buf_size2); - s->gb.size_in_bits= 8*buf_size2; + // Repeat the slice end check from ff_h263_decode_mb with our active + // bitstream size + if (ret != SLICE_ERROR) { + int v = show_bits(&s->gb, 16); + + if (get_bits_count(&s->gb) + 16 > active_bits_size) + v >>= get_bits_count(&s->gb) + 16 - active_bits_size; + + if (!v) + ret = SLICE_END; + } + if (ret != SLICE_ERROR && active_bits_size < get_bits_count(&s->gb) && + 8 * buf_size2 >= get_bits_count(&s->gb)) { + active_bits_size = buf_size2 * 8; + av_log(avctx, AV_LOG_DEBUG, "update size from %d to %d\n", + 8 * buf_size, active_bits_size); ret= SLICE_OK; } - if (ret == SLICE_ERROR || s->gb.size_in_bits < get_bits_count(&s->gb)) { + if (ret == SLICE_ERROR || active_bits_size < get_bits_count(&s->gb)) { av_log(s->avctx, AV_LOG_ERROR, "ERROR at MB %d %d\n", s->mb_x, s->mb_y); return -1; } @@ -612,7 +626,7 @@ static int rv10_decode_packet(AVCodecContext *avctx, ff_er_add_slice(s, start_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, ER_MB_END); - return s->gb.size_in_bits; + return active_bits_size; } static int get_slice_offset(AVCodecContext *avctx, const uint8_t *buf, int n) -- 2.7.4