From: Tristan Madani Date: Wed, 27 May 2026 13:57:50 +0000 (+0000) Subject: netfilter: nft_tunnel: fix use-after-free on object destroy X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=c32b26aaa2f9216520a38b3f4bfeec846eb3eb8a;p=thirdparty%2Flinux.git netfilter: nft_tunnel: fix use-after-free on object destroy 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 Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- diff --git a/net/netfilter/nft_tunnel.c b/net/netfilter/nft_tunnel.c index 0b987bc2132a..68f7cfbbee06 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 = nft_obj_data(obj); - metadata_dst_free(priv->md); + dst_release(&priv->md->dst); } static struct nft_object_type nft_tunnel_obj_type;