From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit ae488c74422fb1dcd807c0201804b3b5e8a322a3 ]
do_tcp_getsockopt() reads rskq_defer_accept while another cpu
might change its value.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230719212857.3943972-9-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/ipv4/tcp.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 4711963413a49..853a33bf8863e 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3009,9 +3009,9 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
case TCP_DEFER_ACCEPT:
/* Translate value in seconds to number of retransmits */
- icsk->icsk_accept_queue.rskq_defer_accept =
- secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
- TCP_RTO_MAX / HZ);
+ WRITE_ONCE(icsk->icsk_accept_queue.rskq_defer_accept,
+ secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
+ TCP_RTO_MAX / HZ));
break;
case TCP_WINDOW_CLAMP:
@@ -3406,8 +3406,9 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
val = (val ? : READ_ONCE(net->ipv4.sysctl_tcp_fin_timeout)) / HZ;
break;
case TCP_DEFER_ACCEPT:
- val = retrans_to_secs(icsk->icsk_accept_queue.rskq_defer_accept,
- TCP_TIMEOUT_INIT / HZ, TCP_RTO_MAX / HZ);
+ val = READ_ONCE(icsk->icsk_accept_queue.rskq_defer_accept);
+ val = retrans_to_secs(val, TCP_TIMEOUT_INIT / HZ,
+ TCP_RTO_MAX / HZ);
break;
case TCP_WINDOW_CLAMP:
val = tp->window_clamp;
--
2.39.2
