[FFmpeg-devel] [PATCH 1/2] avcodec/pngdec: Check length in fdAT

[Michael Niedermayer]

Fixes: 21089/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APNG_fuzzer-5135981419429888
Fixes: out of array read

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/pngdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index 3ce980fc15..39e0569061 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -1252,7 +1252,7 @@ static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
         case MKTAG('f', 'd', 'A', 'T'):
             if (!CONFIG_APNG_DECODER || avctx->codec_id != AV_CODEC_ID_APNG)
                 goto skip_tag;
-            if (!decode_next_dat) {
+            if (!decode_next_dat || length < 4) {
                 ret = AVERROR_INVALIDDATA;
                 goto fail;
             }
-- 
2.17.1