From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 4164245c76ff906c9086758e1c3f87082a7f5ef5 ]
do_tcp_getsockopt() reads tp->keepalive_time 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/20230719212857.3943972-4-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
include/net/tcp.h | 7 +++++--
net/ipv4/tcp.c | 3 ++-
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index e231101e5001b..92de7c049f19e 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1459,9 +1459,12 @@ static inline int keepalive_intvl_when(const struct tcp_sock *tp)
static inline int keepalive_time_when(const struct tcp_sock *tp)
{
struct net *net = sock_net((struct sock *)tp);
+ int val;
- return tp->keepalive_time ? :
- READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time);
+ /* Paired with WRITE_ONCE() in tcp_sock_set_keepidle_locked() */
+ val = READ_ONCE(tp->keepalive_time);
+
+ return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time);
}
static inline int keepalive_probes(const struct tcp_sock *tp)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 39919d1436cea..053e4880d8f0f 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3093,7 +3093,8 @@ int tcp_sock_set_keepidle_locked(struct sock *sk, int val)
if (val < 1 || val > MAX_TCP_KEEPIDLE)
return -EINVAL;
- tp->keepalive_time = val * HZ;
+ /* Paired with WRITE_ONCE() in keepalive_time_when() */
+ WRITE_ONCE(tp->keepalive_time, val * HZ);
if (sock_flag(sk, SOCK_KEEPOPEN) &&
!((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) {
u32 elapsed = keepalive_time_elapsed(tp);
--
2.39.2
