[FFmpeg-cvslog] avcodec/pngdec: Calculate MPNG bytewidth more defensively

[Michael Niedermayer]

ffmpeg | branch: release/2.2 | Michael Niedermayer <michaelni at gmx.at> | Fri Oct  3 17:54:21 2014 +0200| [d1e71ecbb01717a636ebcaf927109f75b7e895ec] | committer: Michael Niedermayer

avcodec/pngdec: Calculate MPNG bytewidth more defensively

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
(cherry picked from commit e830902934a29df05c7af65aef2a480b15f572c4)

Conflicts:

	libavcodec/pngdec.c

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d1e71ecbb01717a636ebcaf927109f75b7e895ec
---

 libavcodec/pngdec.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index d3b1df2..d4f633a 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -841,10 +841,11 @@ static int decode_frame(AVCodecContext *avctx,
             int i, j;
             uint8_t *pd      = p->data[0];
             uint8_t *pd_last = s->last_picture.f->data[0];
+            int ls = FFMIN(av_image_get_linesize(p->format, s->width, 0), s->width * s->bpp);
 
             ff_thread_await_progress(&s->last_picture, INT_MAX, 0);
             for (j = 0; j < s->height; j++) {
-                for (i = 0; i < s->width * s->bpp; i++) {
+                for (i = 0; i < ls; i++) {
                     pd[i] += pd_last[i];
                 }
                 pd      += s->image_linesize;