Commit 46778cd1 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by David S. Miller
Browse files

tcp: Fix data-races around sysctl_tcp_reordering. 



While reading sysctl_tcp_reordering, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4177f545

net/ipv4/tcp.c

+1 −1
Original line number Diff line number Diff line
@@ -441,7 +441,7 @@ void tcp_init_sock(struct sock *sk) 
	tp->snd_cwnd_clamp = ~0;

	tp->mss_cache = TCP_MSS_DEFAULT;



	tp->reordering = sock_net(sk)->ipv4.sysctl_tcp_reordering;

	tp->reordering = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_reordering);

	tcp_assign_congestion_control(sk);



	tp->tsoffset = 0;

net/ipv4/tcp_input.c

+7 −3
Original line number Diff line number Diff line
@@ -2139,6 +2139,7 @@ void tcp_enter_loss(struct sock *sk) 
	struct tcp_sock *tp = tcp_sk(sk);

	struct net *net = sock_net(sk);

	bool new_recovery = icsk->icsk_ca_state < TCP_CA_Recovery;

	u8 reordering;



	tcp_timeout_mark_lost(sk);
@@ -2159,10 +2160,12 @@ void tcp_enter_loss(struct sock *sk) 
	/* Timeout in disordered state after receiving substantial DUPACKs

	 * suggests that the degree of reordering is over-estimated.

	 */

	reordering = READ_ONCE(net->ipv4.sysctl_tcp_reordering);

	if (icsk->icsk_ca_state <= TCP_CA_Disorder &&

	    tp->sacked_out >= net->ipv4.sysctl_tcp_reordering)

	    tp->sacked_out >= reordering)

		tp->reordering = min_t(unsigned int, tp->reordering,

				       net->ipv4.sysctl_tcp_reordering);

				       reordering);



	tcp_set_ca_state(sk, TCP_CA_Loss);

	tp->high_seq = tp->snd_nxt;

	tcp_ecn_queue_cwr(tp);
@@ -3464,7 +3467,8 @@ static inline bool tcp_may_raise_cwnd(const struct sock *sk, const int flag) 
	 * new SACK or ECE mark may first advance cwnd here and later reduce

	 * cwnd in tcp_fastretrans_alert() based on more states.

	 */

	if (tcp_sk(sk)->reordering > sock_net(sk)->ipv4.sysctl_tcp_reordering)

	if (tcp_sk(sk)->reordering >

	    READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_reordering))

		return flag & FLAG_FORWARD_PROGRESS;



	return flag & FLAG_DATA_ACKED;

net/ipv4/tcp_metrics.c

+2 −1
Original line number Diff line number Diff line
@@ -428,7 +428,8 @@ void tcp_update_metrics(struct sock *sk) 
		if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {

			val = tcp_metric_get(tm, TCP_METRIC_REORDERING);

			if (val < tp->reordering &&

			    tp->reordering != net->ipv4.sysctl_tcp_reordering)

			    tp->reordering !=

			    READ_ONCE(net->ipv4.sysctl_tcp_reordering))

				tcp_metric_set(tm, TCP_METRIC_REORDERING,

					       tp->reordering);

		}