Commit fde6f897 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

tcp: fix races in tcp_v[46]_err() 



These functions have races when they:

1) Write sk->sk_err
2) call sk_error_report(sk)
3) call tcp_done(sk)

As described in prior patches in this series:

An smp_wmb() is missing.
We should call tcp_done() before sk_error_report(sk)
to have consistent tcp_poll() results on SMP hosts.

Use tcp_done_with_error() where we centralized the
correct sequence.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Link: https://lore.kernel.org/r/20240528125253.1966136-5-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 5ce4645c

net/ipv4/tcp_ipv4.c

+3 −8
Original line number Diff line number Diff line
@@ -611,15 +611,10 @@ int tcp_v4_err(struct sk_buff *skb, u32 info) 


		ip_icmp_error(sk, skb, err, th->dest, info, (u8 *)th);



		if (!sock_owned_by_user(sk)) {

			WRITE_ONCE(sk->sk_err, err);



			sk_error_report(sk);



			tcp_done(sk);

		} else {

		if (!sock_owned_by_user(sk))

			tcp_done_with_error(sk, err);

		else

			WRITE_ONCE(sk->sk_err_soft, err);

		}

		goto out;

	}

net/ipv6/tcp_ipv6.c

+3 −7
Original line number Diff line number Diff line
@@ -490,14 +490,10 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 


		ipv6_icmp_error(sk, skb, err, th->dest, ntohl(info), (u8 *)th);



		if (!sock_owned_by_user(sk)) {

			WRITE_ONCE(sk->sk_err, err);

			sk_error_report(sk);		/* Wake people up to see the error (see connect in sock.c) */



			tcp_done(sk);

		} else {

		if (!sock_owned_by_user(sk))

			tcp_done_with_error(sk, err);

		else

			WRITE_ONCE(sk->sk_err_soft, err);

		}

		goto out;

	case TCP_LISTEN:

		break;