From eae4b6142223d6f214b97c00bc498884f3b98065 Mon Sep 17 00:00:00 2001 From: Andreas Rheinhardt Date: Thu, 10 Oct 2019 11:47:41 +0200 Subject: [PATCH] avcodec/zmbvenc: Correct offset in buffer MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit zmbvenc allocates a buffer for a picture with padding on all four sides: The stride is choosen so large that it already contains padding on the right; the height also includes padding rows. The padding on the right of each row is also reused as padding for the left of the next row. So one still needs to add padding on the left for the first row. This is done by offsetting the actual pointer used to access the picture from the pointer returned by av_mallocz and the formula for this offset was wrong, because it ignored that a pixel can take more than one byte when calculating the offset resulting from the left padding of the first row. This fixes accesses outside of the allocated buffer that were reported in tickets #7980 and #7994. No writes were ever attempted outside of the buffer. Signed-off-by: Andreas Rheinhardt Reviewed-by: Tomas Härdin Signed-off-by: Michael Niedermayer (cherry picked from commit def04022f4a7058f99e669bfd978d431d79aec18) --- libavcodec/zmbvenc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/libavcodec/zmbvenc.c b/libavcodec/zmbvenc.c index 48871758e0..4d3429393e 100644 --- a/libavcodec/zmbvenc.c +++ b/libavcodec/zmbvenc.c @@ -409,7 +409,7 @@ static av_cold int encode_init(AVCodecContext *avctx) */ c->pstride = FFALIGN((avctx->width + c->lrange) * c->bypp, 16); prev_size = FFALIGN(c->lrange * c->bypp, 16) + c->pstride * (c->lrange + avctx->height + c->urange); - prev_offset = FFALIGN(c->lrange, 16) + c->pstride * c->lrange; + prev_offset = FFALIGN(c->lrange * c->bypp, 16) + c->pstride * c->lrange; if (!(c->prev_buf = av_mallocz(prev_size))) { av_log(avctx, AV_LOG_ERROR, "Can't allocate picture.\n"); return AVERROR(ENOMEM);