netfilter: nf_queue: don't assume sk is full socket

stable inclusion
from linux-4.19.233
commit 6d9719ef61a99d1ed750b510d32620a6c4bb7397
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5646A
CVE: NA

--------------------------------

commit 747670fd upstream.

There is no guarantee that state->sk refers to a full socket.

If refcount transitions to 0, sock_put calls sk_free which then ends up
with garbage fields.

I'd like to thank Oleksandr Natalenko and Jiri Benc for considerable
debug work and pointing out state->sk oddities.

Fixes: ca6fb065 ("tcp: attach SYNACK messages to request sockets instead of listener")
Tested-by: NOleksandr Natalenko <oleksandr@redhat.com>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

net/netfilter/nf_queue.c

@@ -46,6 +46,15 @@ void nf_unregister_queue_handler(struct net *net)
 }
 EXPORT_SYMBOL(nf_unregister_queue_handler);
 
+static void nf_queue_sock_put(struct sock *sk)
+{
+#ifdef CONFIG_INET
+	sock_gen_put(sk);
+#else
+	sock_put(sk);
+#endif
+}
+
 void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
 {
 	struct nf_hook_state *state = &entry->state;
@@ -56,7 +65,7 @@ void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
 	if (state->out)
 		dev_put(state->out);
 	if (state->sk)
-		sock_put(state->sk);
+		nf_queue_sock_put(state->sk);
 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
 	if (entry->skb->nf_bridge) {
 		struct net_device *physdev;