From 8540c00f1bdbf85d62bfa521aa8ae8880a727fb1 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Tue, 20 Oct 2026 15:57:12 +0200
Subject: [PATCH] avcodec/hevc: keep the active VPS when clearing a layer's SPS

set_sps() with a NULL SPS released s->vps before returning, also when only
a non-base layer was cleared while the base layer keeps decoding. The next
base-layer frame then dereferenced the NULL VPS in ff_hevc_is_alpha_video().
Release s->vps only when a new SPS is installed alongside it.

Assisted-by: Fairy
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/hevc/hevcdec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/hevc/hevcdec.c b/libavcodec/hevc/hevcdec.c
index 14fdadc7cc..f5f0cf7f10 100644
--- a/libavcodec/hevc/hevcdec.c
+++ b/libavcodec/hevc/hevcdec.c
@@ -768,6 +768,8 @@ static int set_sps(HEVCContext *s, HEVCLayerContext *l, const HEVCSPS *sps)
     if (!sps)
         return 0;
 
+    av_refstruct_unref(&s->vps);
+
     ret = pic_arrays_init(l, sps);
     if (ret < 0)
         goto fail;