Bluetooth: L2CAP: do not leave dangling sk pointer on error in l2cap_sock_create()

bt_sock_alloc() allocates the sk object and attaches it to the provided
sock object. On error l2cap_sock_alloc() frees the sk object, but the
dangling pointer is still attached to the sock object, which may create
use-after-free in other code.

Signed-off-by: Ignat Korchagin <[email protected]>
Reviewed-by: Kuniyuki Iwashima <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: ignatk

net/bluetooth/l2cap_sock.c

@@ -1886,6 +1886,7 @@ static struct sock *l2cap_sock_alloc(struct net *net, struct socket *sock,
 	chan = l2cap_chan_create();
 	if (!chan) {
 		sk_free(sk);
+		sock->sk = NULL;
 		return NULL;
 	}