ffmpeg | branch: master | Niklesh <niklesh.lalw...@iitb.ac.in> | Tue May 19 18:40:55 2015 +0530| [b44a55ad2d182dc5dce09609badfb6dcb575e632] | committer: Philip Langdale
Fix movtext crashes caused due to lack of proper bounds checking Signed-off-by: Niklesh <niklesh.lalw...@iitb.ac.in> > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b44a55ad2d182dc5dce09609badfb6dcb575e632 --- libavcodec/movtextdec.c | 18 +++++++++++++++--- 1 file 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); _______________________________________________ ffmpeg-cvslog mailing list ffmpeg-cvslog@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-cvslog