From 6b657ac7889738b9ab38924cca4e7c418f6fbc38 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Tue, 16 Apr 2013 16:41:21 +0200 Subject: [PATCH] avcodec/c93: Check for block overlap. Fixes overlapping memcpy() Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind Signed-off-by: Michael Niedermayer --- libavcodec/c93.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/libavcodec/c93.c b/libavcodec/c93.c index 9aaa3ee780..c51f2fa9de 100644 --- a/libavcodec/c93.c +++ b/libavcodec/c93.c @@ -168,7 +168,14 @@ static int decode_frame(AVCodecContext *avctx, void *data, case C93_4X4_FROM_PREV: for (j = 0; j < 8; j += 4) { for (i = 0; i < 8; i += 4) { - offset = bytestream2_get_le16(&gb); + int offset = bytestream2_get_le16(&gb); + int from_x = offset % WIDTH; + int from_y = offset / WIDTH; + if (block_type == C93_4X4_FROM_CURR && from_y == y+j && + (FFABS(from_x - x-i) < 4 || FFABS(from_x - x-i) > WIDTH-4)) { + avpriv_request_sample(avctx, "block overlap %d %d %d %d\n", from_x, x+i, from_y, y+j); + return AVERROR_INVALIDDATA; + } if ((ret = copy_block(avctx, &out[j*stride+i], copy_from, offset, 4, stride)) < 0) return ret;