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tcp: Fix a data-race around sysctl_tcp_ecn_fallback.

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

Fixes: 492135557d ("tcp: add rfc3168, section 6.1.1.1. fallback")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kuniyuki Iwashima 2022-07-11 17:15:31 -07:00 committed by David S. Miller
parent 4785a66702
commit 12b8d9ca7e
2 changed files with 3 additions and 1 deletions
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2
net/ipv4/sysctl_net_ipv4.c
View File

@ -685,6 +685,8 @@ static struct ctl_table ipv4_net_table[] = {
.maxlen = sizeof(u8),
.mode = 0644,
.proc_handler = proc_dou8vec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
{
.procname = "ip_dynaddr",

2
net/ipv4/tcp_output.c
View File

@ -346,7 +346,7 @@ static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb)
static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb)
{
if (sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback)
if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback))
/* tp->ecn_flags are cleared at a later point in time when
* SYN ACK is ultimatively being received.
*/