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([2001:41d0:303:db6b::]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45edb5c2323sm6388642f8f.34.2026.05.27.06.57.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 May 2026 06:57:51 -0700 (PDT) From: Tristan Madani To: Pablo Neira Ayuso , Florian Westphal Cc: Phil Sutter , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Tristan Madani Subject: [PATCH] netfilter: nft_tunnel: fix use-after-free on object destroy Date: Wed, 27 May 2026 13:57:50 +0000 Message-ID: <20260527135751.1031891-1-tristmd@gmail.com> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Tristan Madani nft_tunnel_obj_destroy() calls metadata_dst_free() which directly kfree()s the metadata_dst, ignoring the dst_entry refcount. Packets that took a reference via dst_hold() in nft_tunnel_obj_eval() and are still queued (e.g. in a netem qdisc) are left with a dangling pointer. When these packets are eventually dequeued, dst_release() operates on freed memory. Replace metadata_dst_free() with dst_release() so the metadata_dst is freed only after all references are dropped. The dst subsystem already handles metadata_dst cleanup in dst_destroy() when DST_METADATA is set. Fixes: af308b94a2a4 ("netfilter: nf_tables: add tunnel support") Cc: stable@vger.kernel.org Signed-off-by: Tristan Madani Reviewed-by: Fernando Fernandez Mancera --- net/netfilter/nft_tunnel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netfilter/nft_tunnel.c b/net/netfilter/nft_tunnel.c index 0b987bc2132ae..68f7cfbbee063 100644 --- a/net/netfilter/nft_tunnel.c +++ b/net/netfilter/nft_tunnel.c @@ -676,7 +676,7 @@ static void nft_tunnel_obj_destroy(const struct nft_ctx= *ctx, { struct nft_tunnel_obj *priv =3D nft_obj_data(obj); =20 - metadata_dst_free(priv->md); + dst_release(&priv->md->dst); } =20 static struct nft_object_type nft_tunnel_obj_type; --=20 2.47.3