avcodec/pngdec: Check IHDR/IDAT order

Fixes out of array access
Fixes: asan_heap-oob_20a6c26_2690_cov_3434532168_mail.png
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 79ceaf827be0b070675d4cd0a55c3386542defd8)

Conflicts:

	libavcodec/pngdec.c

diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index 22c50b7..a8c1d88 100644 (file)
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -418,6 +418,12 @@ static int decode_frame(AVCodecContext *avctx,
         case MKTAG('I', 'H', 'D', 'R'):
             if (length != 13)
                 goto fail;
+
+            if (s->state & PNG_IDAT) {
+                av_log(avctx, AV_LOG_ERROR, "IHDR after IDAT\n");
+                goto fail;
+            }
+
             s->width = bytestream_get_be32(&s->bytestream);
             s->height = bytestream_get_be32(&s->bytestream);
             if(av_image_check_size(s->width, s->height, 0, avctx)){