On 29/09/2020 17:17, James Almer wrote:
On 9/29/2020 12:57 PM, Mark Thompson wrote:
On 25/09/2020 15:43, James Almer wrote:
Fixes: member access within null pointer of type 'TileGroupInfo' (aka
'struct TileGroupInfo')
Fixes:
25725/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AV1_fuzzer-5166692706287616
Found-by: continuous fuzzing process
https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: James Almer <jamr...@gmail.com>
---
libavcodec/av1dec.c | 30 ++++++++++++++++--------------
1 file changed, 16 insertions(+), 14 deletions(-)
diff --git a/libavcodec/av1dec.c b/libavcodec/av1dec.c
index 07026b7aeb..e5cfc3f2f2 100644
--- a/libavcodec/av1dec.c
+++ b/libavcodec/av1dec.c
@@ -381,6 +381,20 @@ fail:
return AVERROR(ENOMEM);
}
+static void av1_decode_flush(AVCodecContext *avctx)
+{
+ AV1DecContext *s = avctx->priv_data;
+
+ for (int i = 0; i < FF_ARRAY_ELEMS(s->ref); i++)
+ av1_frame_unref(avctx, &s->ref[i]);
+
+ av1_frame_unref(avctx, &s->cur_frame);
+ s->raw_frame_header = NULL;
+ s->raw_seq = NULL;
+
+ ff_cbs_flush(s->cbc);
+}
+
static av_cold int av1_decode_free(AVCodecContext *avctx)
{
AV1DecContext *s = avctx->priv_data;
@@ -841,23 +855,11 @@ static int av1_decode_frame(AVCodecContext
*avctx, void *frame,
end:
ff_cbs_fragment_reset(&s->current_obu);
+ if (ret < 0)
+ av1_decode_flush(avctx);
return ret;
}
-static void av1_decode_flush(AVCodecContext *avctx)
-{
- AV1DecContext *s = avctx->priv_data;
-
- for (int i = 0; i < FF_ARRAY_ELEMS(s->ref); i++)
- av1_frame_unref(avctx, &s->ref[i]);
-
- av1_frame_unref(avctx, &s->cur_frame);
- s->raw_frame_header = NULL;
- s->raw_seq = NULL;
-
- ff_cbs_flush(s->cbc);
-}
-
AVCodec ff_av1_decoder = {
.name = "av1",
.long_name = NULL_IF_CONFIG_SMALL("Alliance for Open
Media AV1"),
This seems questionable - if you have some packet loss and lose an
intermediate frame, I don't think you want to throw away all the old
state since it may be able to continue from an earlier frame which was
received correctly.
If a frame was not parsed correctly, then the reference frame state from
then on will be invalid. Especially if ff_cbs_read_packet() is what
failed, considering everything after the corrupt OBU within the TU will
be discarded by CBS.
Only the reference frame state which the frame would have modified has changed,
which need not be all of it if the encoder knows it is going to be sending over
an unreliable channel.
Also intra refresh, though I haven't seen that implemented in an AV1 encoder
yet.
I can replace this to simply setting raw_frame_header to NULL if you
prefer, but for reference, dav1d (the decoder that hopefully will
eventually be ported into this native decoder) throws the entire state
away on a frame decoding failure.
I think that answer is preferable, though I guess it could just be ignored for
now and fixed when it comes up in future. (Presumably noone has tried to use
dav1d for these sorts of cases yet.)
- Mark
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