dsicinav: Check for out of bounds reads

Signed-off-by: Janne Grunau <janne-libav@jannau.net>

libavcodec/dsicinav.c

@@ -216,6 +216,8 @@ static int cinvideo_decode_frame(AVCodecContext *avctx,
     bitmap_frame_size = buf_size - 4;
 
     /* handle palette */
+    if (bitmap_frame_size < palette_colors_count * (3 + (palette_type != 0)))
+        return AVERROR_INVALIDDATA;
     if (palette_type == 0) {
         for (i = 0; i < palette_colors_count; ++i) {
             cin->palette[i] = bytestream_get_le24(&buf);