avcodec/msrle: use av_image_get_linesize() to calculate the linesize

Fixes out of array access
Fixes: 14a74a0a2dc67ede543f0e35d834fbbe-asan_heap-oob_49572c_556_cov_215466444_44_001_engine_room.mov
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/msrle.c

@@ -35,6 +35,7 @@
 #include "avcodec.h"
 #include "internal.h"
 #include "msrledec.h"
+#include "libavutil/imgutils.h"
 
 typedef struct MsrleContext {
     AVCodecContext *avctx;
@@ -110,7 +111,7 @@ static int msrle_decode_frame(AVCodecContext *avctx,
 
     /* FIXME how to correctly detect RLE ??? */
     if (avctx->height * istride == avpkt->size) { /* assume uncompressed */
-        int linesize = (avctx->width * avctx->bits_per_coded_sample + 7) / 8;
+        int linesize = av_image_get_linesize(avctx->pix_fmt, avctx->width, 0);
         uint8_t *ptr = s->frame->data[0];
         uint8_t *buf = avpkt->data + (avctx->height-1)*istride;
         int i, j;