dfa: check for invalid access in decode_wdlt().

This can happen when the number of skipped lines is not consistent with
the number of coded lines.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org

diff --git a/libavcodec/dfa.c b/libavcodec/dfa.c
index bbe4ce2888b3a4fe02680e7aa74edd28d0499628..6619b98301858d33dbad6b6f5cd25b249c19f464 100644 (file)
--- a/libavcodec/dfa.c
+++ b/libavcodec/dfa.c
@@ -255,6 +255,8 @@ static int decode_wdlt(GetByteContext *gb, uint8_t *frame, int width, int height
             segments = bytestream2_get_le16(gb);
         }
         line_ptr = frame;
+        if (frame_end - frame < width)
+            return AVERROR_INVALIDDATA;
         frame += width;
         y++;
         while (segments--) {