From e42fc6263379176869dd9a6467e37f9956d56431 Mon Sep 17 00:00:00 2001 From: Andreas Rheinhardt Date: Tue, 15 Sep 2020 03:03:18 +0200 Subject: [PATCH] avcodec/mobiclip: Fix heap-buffer-overflow The MobiClip decoder uses adjacent pixels for prediction; yet when accessing the left pixel, it was forgotten to clip the x coordinate. This results in an heap-buffer-overflow. It can e.g. be reproduced with the sample from https://samples.ffmpeg.org/V-codecs/MOHD/crap.avi when forcing the video decoder to mobiclip. Reviewed-by: Paul B Mahol Signed-off-by: Andreas Rheinhardt --- libavcodec/mobiclip.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/libavcodec/mobiclip.c b/libavcodec/mobiclip.c index 8758e7f617..47387fce90 100644 --- a/libavcodec/mobiclip.c +++ b/libavcodec/mobiclip.c @@ -905,7 +905,7 @@ static int predict_intra(AVCodecContext *avctx, AVFrame *frame, int ax, int ay, int arr1[16]; int arr2[16]; uint8_t *top = frame->data[plane] + FFMAX(ay - 1, 0) * frame->linesize[plane] + ax; - uint8_t *left = frame->data[plane] + ay * frame->linesize[plane] + ax - 1; + uint8_t *left = frame->data[plane] + ay * frame->linesize[plane] + FFMAX(ax - 1, 0); int bottommost = frame->data[plane][(ay + size - 1) * frame->linesize[plane] + FFMAX(ax - 1, 0)]; int rightmost = frame->data[plane][FFMAX(ay - 1, 0) * frame->linesize[plane] + ax + size - 1]; int avg = (bottommost + rightmost + 1) / 2 + 2 * get_se_golomb(gb);