From: Eric Dumazet edumazet@google.com
[ 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@google.com Link: https://lore.kernel.org/r/20230719212857.3943972-5-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 f9a24f48fa986..b737ce77f7062 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1473,9 +1473,14 @@ 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 54219e2080019..8fe1098b183d0 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3350,7 +3350,7 @@ 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; } @@ -3564,7 +3564,7 @@ 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)