[PATCH 5.10 260/545] tcp: Fix data-races around sysctl_tcp_l3mdev_accept.

Greg Kroah-Hartman
2022-08-19T16:19:17Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 08a75f10679470552a3a443f9aefd1399604d31d ]

While reading sysctl_tcp_l3mdev_accept, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 6dd9a14e92e5 ("net: Allow accepted sockets to be bound to l3mdev domain")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/inet_hashtables.h | 2 +-
include/net/inet_sock.h | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 816851807fa8..1a3bf9726b75 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -201,7 +201,7 @@ static inline bool inet_sk_bound_dev_eq(struct net *net, int bound_dev_if,
int dif, int sdif)
{
#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
- return inet_bound_dev_eq(!!net->ipv4.sysctl_tcp_l3mdev_accept,
+ return inet_bound_dev_eq(!!READ_ONCE(net->ipv4.sysctl_tcp_l3mdev_accept),
bound_dev_if, dif, sdif);
#else
return inet_bound_dev_eq(true, bound_dev_if, dif, sdif);
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 886ed0950b7f..4908513c6dfb 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -121,7 +121,7 @@ static inline int inet_request_bound_dev_if(const struct sock *sk,
#ifdef CONFIG_NET_L3_MASTER_DEV
struct net *net = sock_net(sk);

- if (!bound_dev_if && net->ipv4.sysctl_tcp_l3mdev_accept)
+ if (!bound_dev_if && READ_ONCE(net->ipv4.sysctl_tcp_l3mdev_accept))
return l3mdev_master_ifindex_by_index(net, skb->skb_iif);
#endif

@@ -133,7 +133,7 @@ static inline int inet_sk_bound_l3mdev(const struct sock *sk)
#ifdef CONFIG_NET_L3_MASTER_DEV
struct net *net = sock_net(sk);

- if (!net->ipv4.sysctl_tcp_l3mdev_accept)
+ if (!READ_ONCE(net->ipv4.sysctl_tcp_l3mdev_accept))
return l3mdev_master_ifindex_by_index(net,
sk->sk_bound_dev_if);
#endif
--
2.35.1