tcp: Fix a data-race around sysctl_tcp_max_orphans.

[ Upstream commit 47e6ab24e8c6e3ca10ceb5835413f401f90de4bf ]

While reading sysctl_tcp_max_orphans, it can be changed concurrently.
So, we need to add READ_ONCE() to avoid a data-race.

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>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f79b5a9..4ac53c8 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2714,7 +2714,8 @@ static void tcp_orphan_update(struct timer_list *unused)
 
 static bool tcp_too_many_orphans(int shift)
 {
-       return READ_ONCE(tcp_orphan_cache) << shift > sysctl_tcp_max_orphans;
+       return READ_ONCE(tcp_orphan_cache) << shift >
+               READ_ONCE(sysctl_tcp_max_orphans);
 }
 
 bool tcp_check_oom(struct sock *sk, int shift)