[FFmpeg-cvslog] avcodec/pngdec: Do not pass AVFrame into global header decode

[Michael Niedermayer]

ffmpeg | branch: release/4.4 | Michael Niedermayer <michael at niedermayer.cc> | Sun Apr 16 15:06:59 2023 +0200| [f73735747c7fedbd5216de38284e71e7ae148171] | committer: Michael Niedermayer

avcodec/pngdec: Do not pass AVFrame into global header decode

The global header should not contain a frame, and decoding it
would result in leaks

Fixes: memleak
Fixes: 45982/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APNG_fuzzer-6603443149340672

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit d31d4f32283f765c79d6e127d31ee2c37a0acef7)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=f73735747c7fedbd5216de38284e71e7ae148171
---

 libavcodec/pngdec.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index 042ad1b062..8ef4297904 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -643,6 +643,8 @@ static int decode_idat_chunk(AVCodecContext *avctx, PNGDecContext *s,
     int ret;
     size_t byte_depth = s->bit_depth > 8 ? 2 : 1;
 
+    if (!p)
+        return AVERROR_INVALIDDATA;
     if (!(s->hdr_state & PNG_IHDR)) {
         av_log(avctx, AV_LOG_ERROR, "IDAT without IHDR\n");
         return AVERROR_INVALIDDATA;
@@ -1375,6 +1377,9 @@ skip_tag:
     }
 exit_loop:
 
+    if (!p)
+        return AVERROR_INVALIDDATA;
+
     if (avctx->codec_id == AV_CODEC_ID_PNG &&
         avctx->skip_frame == AVDISCARD_ALL) {
         return 0;
@@ -1614,7 +1619,7 @@ static int decode_frame_apng(AVCodecContext *avctx,
         s->zstream.zfree  = ff_png_zfree;
 
         bytestream2_init(&s->gb, avctx->extradata, avctx->extradata_size);
-        if ((ret = decode_frame_common(avctx, s, p, avpkt)) < 0)
+        if ((ret = decode_frame_common(avctx, s, NULL, avpkt)) < 0)
             goto end;
     }