avcodec/rawdec: Check side data size before use

Fixes out of array read
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/rawdec.c

@@ -364,9 +364,16 @@ static int raw_decode(AVCodecContext *avctx, void *data, int *got_frame,
     }
 
     if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
+        int pal_size;
         const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE,
-                                                     NULL);
+                                                     &pal_size);
         int ret;
+
+        if (pal_size != AVPALETTE_SIZE) {
+            av_log(avctx, AV_LOG_ERROR, "Palette size %d is wrong\n", pal_size);
+            pal = NULL;
+        }
+
         if (!context->palette)
             context->palette = av_buffer_alloc(AVPALETTE_SIZE);
         if (!context->palette) {