[FFmpeg-devel] [PATCH v2 1/2] avcodec/av1dec: Fix segfault upon allocation error

[Andreas Rheinhardt]

Up until now, the AV1 decoder always checks before calling its wrapper
around ff_thread_release_buffer() whether the ThreadFrame was used at
all, i.e. it checked whether the first data buffer of the AVFrame
contained therein is NULL or not. Yet this presumes that the AVFrame has
been successfully allocated, even though this can of course fail; and if
it did, one would encounter a segfault.
Fix this by removing the checks altogether: ff_thread_release_buffer()
can handle both unallocated as well as empty frames (since commit
f6774f905fb3cfdc319523ac640be30b14c1bc55).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
---
Removing the checks is based upon a suggestion by James Almer. I have
not removed the checks from the other callers of av1_frame_unref() as I
don't know how probable it is for the frame to be empty at this point.
I tested this as well as I can, but I have no hardware with AV1 hardware
acceleration.

 libavcodec/av1dec.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/libavcodec/av1dec.c b/libavcodec/av1dec.c
index bd8acdaafe..871db76b4d 100644
--- a/libavcodec/av1dec.c
+++ b/libavcodec/av1dec.c
@@ -388,12 +388,10 @@ static av_cold int av1_decode_free(AVCodecContext *avctx)
     AV1DecContext *s = avctx->priv_data;
 
     for (int i = 0; i < FF_ARRAY_ELEMS(s->ref); i++) {
-        if (s->ref[i].tf.f->buf[0])
-            av1_frame_unref(avctx, &s->ref[i]);
+        av1_frame_unref(avctx, &s->ref[i]);
         av_frame_free(&s->ref[i].tf.f);
     }
-    if (s->cur_frame.tf.f->buf[0])
-        av1_frame_unref(avctx, &s->cur_frame);
+    av1_frame_unref(avctx, &s->cur_frame);
     av_frame_free(&s->cur_frame.tf.f);
 
     av_buffer_unref(&s->seq_ref);
-- 
2.25.1