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Commit f240d0ca authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Greg Kroah-Hartman
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tcp: Fix data-races around sysctl_tcp_dsack. 



commit 58ebb1c8b35a8ef38cd6927431e0fa7b173a632d upstream.

While reading sysctl_tcp_dsack, 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>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b9f937d3

net/ipv4/tcp_input.c

+2 −2
Original line number Diff line number Diff line
@@ -4260,7 +4260,7 @@ static void tcp_dsack_set(struct sock *sk, u32 seq, u32 end_seq) 
{

	struct tcp_sock *tp = tcp_sk(sk);



	if (tcp_is_sack(tp) && sock_net(sk)->ipv4.sysctl_tcp_dsack) {

	if (tcp_is_sack(tp) && READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_dsack)) {

		int mib_idx;



		if (before(seq, tp->rcv_nxt))
@@ -4306,7 +4306,7 @@ static void tcp_send_dupack(struct sock *sk, const struct sk_buff *skb) 
		NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOST);

		tcp_enter_quickack_mode(sk, TCP_MAX_QUICKACKS);



		if (tcp_is_sack(tp) && sock_net(sk)->ipv4.sysctl_tcp_dsack) {

		if (tcp_is_sack(tp) && READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_dsack)) {

			u32 end_seq = TCP_SKB_CB(skb)->end_seq;



			tcp_rcv_spurious_retrans(sk, skb);