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author | Niklesh <niklesh.lalwani@iitb.ac.in> | 2015-05-19 18:22:55 +0530 |
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committer | Philip Langdale <philipl@overt.org> | 2015-05-19 20:15:15 -0700 |
commit | b44a55ad2d182dc5dce09609badfb6dcb575e632 (patch) | |
tree | 77d2cfc1097dbf2ba8056f6cfde7de6c305910f7 /libavcodec | |
parent | b8e7f2b277b8c2ae2705ff10d6bafb696655e745 (diff) | |
download | ffmpeg-streaming-b44a55ad2d182dc5dce09609badfb6dcb575e632.zip ffmpeg-streaming-b44a55ad2d182dc5dce09609badfb6dcb575e632.tar.gz |
Fix movtext crashes caused due to lack of proper bounds checking
Signed-off-by: Niklesh <niklesh.lalwani@iitb.ac.in>
Diffstat (limited to 'libavcodec')
-rw-r--r-- | libavcodec/movtextdec.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/libavcodec/movtextdec.c b/libavcodec/movtextdec.c index 3059599..53ffef0 100644 --- a/libavcodec/movtextdec.c +++ b/libavcodec/movtextdec.c @@ -96,7 +96,7 @@ static int mov_text_decode_frame(AVCodecContext *avctx, char *ptr = avpkt->data; char *end; //char *ptr_temp; - int text_length, tsmb_type, style_entries, tsmb_size; + int text_length, tsmb_type, style_entries, tsmb_size, tracksize; int **style_start = {0,}; int **style_end = {0,}; int **style_flags = {0,}; @@ -135,20 +135,31 @@ static int mov_text_decode_frame(AVCodecContext *avctx, (AVRational){1,100}); tsmb_size = 0; + tracksize = 2 + text_length; // Note that the spec recommends lines be no longer than 2048 characters. av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED); if (text_length + 2 != avpkt->size) { - while (text_length + 2 + tsmb_size < avpkt->size) { - tsmb = ptr + text_length + tsmb_size; + while (tracksize + 8 <= avpkt->size) { + // A box is a minimum of 8 bytes. + tsmb = ptr + tracksize - 2; tsmb_size = AV_RB32(tsmb); tsmb += 4; tsmb_type = AV_RB32(tsmb); tsmb += 4; + if (tracksize + tsmb_size > avpkt->size) + break; + if (tsmb_type == MKBETAG('s','t','y','l')) { + if (tracksize + 10 > avpkt->size) + break; style_entries = AV_RB16(tsmb); tsmb += 2; + // A single style record is of length 12 bytes. + if (tracksize + 10 + style_entries * 12 > avpkt->size) + break; + for(i = 0; i < style_entries; i++) { style_pos = av_malloc(4); *style_pos = AV_RB16(tsmb); @@ -176,6 +187,7 @@ static int mov_text_decode_frame(AVCodecContext *avctx, av_freep(&style_end); av_freep(&style_flags); } + tracksize = tracksize + tsmb_size; } } else text_to_ass(&buf, ptr, end, NULL, NULL, 0, 0); |