From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 5ecf9d4f52ff2f1d4d44c9b68bc75688e82f13b4 ]
do_tcp_getsockopt() reads tp->keepalive_intvl 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/20230719212857.3943972-5-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
include/net/tcp.h | 9 +++++++--
net/ipv4/tcp.c | 4 ++--
2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 92de7c049f19e..428f84f6e0d0c 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1451,9 +1451,14 @@ void tcp_leave_memory_pressure(struct sock *sk);
static inline int keepalive_intvl_when(const struct tcp_sock *tp)
{
struct net *net = sock_net((struct sock *)tp);
+ int val;
+
+ /* Paired with WRITE_ONCE() in tcp_sock_set_keepintvl()
+ * and do_tcp_setsockopt().
+ */
+ val = READ_ONCE(tp->keepalive_intvl);
- return tp->keepalive_intvl ? :
- READ_ONCE(net->ipv4.sysctl_tcp_keepalive_intvl);
+ return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_intvl);
}
static inline int keepalive_time_when(const struct tcp_sock *tp)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 053e4880d8f0f..b5a05b0984146 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3126,7 +3126,7 @@ int tcp_sock_set_keepintvl(struct sock *sk, int val)
return -EINVAL;
lock_sock(sk);
- tcp_sk(sk)->keepalive_intvl = val * HZ;
+ WRITE_ONCE(tcp_sk(sk)->keepalive_intvl, val * HZ);
release_sock(sk);
return 0;
}
@@ -3324,7 +3324,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname,
if (val < 1 || val > MAX_TCP_KEEPINTVL)
err = -EINVAL;
else
- tp->keepalive_intvl = val * HZ;
+ WRITE_ONCE(tp->keepalive_intvl, val * HZ);
break;
case TCP_KEEPCNT:
if (val < 1 || val > MAX_TCP_KEEPCNT)
--
2.39.2
