[PATCH 5.18 111/231] tcp: Fix a data-race around sysctl_max_tw_buckets.

Greg Kroah-Hartman
2022-07-19T12:58:51Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 6f605b57f3782114e330e108ce1903ede22ec675 ]

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

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
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/ipv4/inet_timewait_sock.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 0ec501845cb3..47ccc343c9fb 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -156,7 +156,8 @@ struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk,
{
struct inet_timewait_sock *tw;

- if (refcount_read(&dr->tw_refcount) - 1 >= dr->sysctl_max_tw_buckets)
+ if (refcount_read(&dr->tw_refcount) - 1 >=
+ READ_ONCE(dr->sysctl_max_tw_buckets))
return NULL;

tw = kmem_cache_alloc(sk->sk_prot_creator->twsk_prot->twsk_slab,
--
2.35.1