netlink: Fix rmem check in netlink_broadcast_deliver().

We need to allow queuing at least one skb even when skb is
larger than sk->sk_rcvbuf.

The cited commit made a mistake while converting a condition
in netlink_broadcast_deliver().

Let's correct the rmem check for the allow-one-skb rule.

Fixes: ae8f160 ("netlink: Fix wraparounds of sk->sk_rmem_alloc.")
Signed-off-by: Kuniyuki Iwashima <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: q2ven

net/netlink/af_netlink.c

@@ -1395,7 +1395,7 @@ static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
 	rmem = atomic_add_return(skb->truesize, &sk->sk_rmem_alloc);
 	rcvbuf = READ_ONCE(sk->sk_rcvbuf);
 
-	if ((rmem != skb->truesize || rmem <= rcvbuf) &&
+	if ((rmem == skb->truesize || rmem <= rcvbuf) &&
 	    !test_bit(NETLINK_S_CONGESTED, &nlk->state)) {
 		netlink_skb_set_owner_r(skb, sk);
 		__netlink_sendskb(sk, skb);