[PATCH 5.15 093/201] tcp: Fix data-races around sysctl_tcp_migrate_req.

Greg Kroah-Hartman
2022-07-27T17:11:04Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 4177f545895b1da08447a80692f30617154efa6e ]

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

Fixes: f9ac779f881c ("net: Introduce net.ipv4.tcp_migrate_req.")
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>
---
net/core/sock_reuseport.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c
index 3f00a28fe762..5daa1fa54249 100644
--- a/net/core/sock_reuseport.c
+++ b/net/core/sock_reuseport.c
@@ -387,7 +387,7 @@ void reuseport_stop_listen_sock(struct sock *sk)
prog = rcu_dereference_protected(reuse->prog,
lockdep_is_held(&reuseport_lock));

- if (sock_net(sk)->ipv4.sysctl_tcp_migrate_req ||
+ if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_migrate_req) ||
(prog && prog->expected_attach_type == BPF_SK_REUSEPORT_SELECT_OR_MIGRATE)) {
/* Migration capable, move sk from the listening section
* to the closed section.
@@ -545,7 +545,7 @@ struct sock *reuseport_migrate_sock(struct sock *sk,
hash = migrating_sk->sk_hash;
prog = rcu_dereference(reuse->prog);
if (!prog || prog->expected_attach_type != BPF_SK_REUSEPORT_SELECT_OR_MIGRATE) {
- if (sock_net(sk)->ipv4.sysctl_tcp_migrate_req)
+ if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_migrate_req))
goto select_by_hash;
goto failure;
}
--
2.35.1