lavc/pngdec: improve chunk length check

The length does not cover the chunk type or CRC.
4 years ago · ae08eec6a1
parent 8e4390de48
commit ae08eec6a1
1 changed files with 1 additions and 1 deletions
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@ -1217,7 +1217,7 @@ static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
        }

        length = bytestream2_get_be32(&s->gb);
-        if (length > 0x7fffffff || length > bytestream2_get_bytes_left(&s->gb)) {
+        if (length > 0x7fffffff || length + 8 > bytestream2_get_bytes_left(&s->gb)) {
            av_log(avctx, AV_LOG_ERROR, "chunk too big\n");
            ret = AVERROR_INVALIDDATA;
            goto fail;