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Commit d9b55bf7 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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tcp: annotate tp->urg_seq lockless reads 



There two places where we fetch tp->urg_seq while
this field can change from IRQ or other cpu.

We need to add READ_ONCE() annotations, and also make
sure write side use corresponding WRITE_ONCE() to avoid
store-tearing.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e0d694d6

net/ipv4/tcp.c

+3 −2
Original line number Diff line number Diff line
@@ -546,7 +546,7 @@ __poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait) 
	    (state != TCP_SYN_RECV || rcu_access_pointer(tp->fastopen_rsk))) {

		int target = sock_rcvlowat(sk, 0, INT_MAX);



		if (tp->urg_seq == READ_ONCE(tp->copied_seq) &&

		if (READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq) &&

		    !sock_flag(sk, SOCK_URGINLINE) &&

		    tp->urg_data)

			target++;
@@ -607,7 +607,8 @@ int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg) 
		unlock_sock_fast(sk, slow);

		break;

	case SIOCATMARK:

		answ = tp->urg_data && tp->urg_seq == READ_ONCE(tp->copied_seq);

		answ = tp->urg_data &&

		       READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq);

		break;

	case SIOCOUTQ:

		if (sk->sk_state == TCP_LISTEN)

net/ipv4/tcp_input.c

+1 −1
Original line number Diff line number Diff line
@@ -5356,7 +5356,7 @@ static void tcp_check_urg(struct sock *sk, const struct tcphdr *th) 
	}



	tp->urg_data = TCP_URG_NOTYET;

	tp->urg_seq = ptr;

	WRITE_ONCE(tp->urg_seq, ptr);



	/* Disable header prediction. */

	tp->pred_flags = 0;