From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Fri, 15 Jul 2022 17:17:42 +0000 (-0700)
Subject: igmp: Fix a data-race around sysctl_igmp_max_memberships.
X-Git-Tag: baikal/aarch64/sdk5.9~2593
X-Git-Url: https://git.baikalelectronics.ru/?a=commitdiff_plain;h=4e16c971208adc92dd8a5939aba6be74cfea2f56;p=kernel.git

igmp: Fix a data-race around sysctl_igmp_max_memberships.

[ Upstream commit 3d416fd9eece9d682b0ac5f60a9ec3514d918b9e ]

While reading sysctl_igmp_max_memberships, 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>
---

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 7cd444d75c3dd..660b41040c771 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -2199,7 +2199,7 @@ static int __ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr,
 		count++;
 	}
 	err = -ENOBUFS;
-	if (count >= net->ipv4.sysctl_igmp_max_memberships)
+	if (count >= READ_ONCE(net->ipv4.sysctl_igmp_max_memberships))
 		goto done;
 	iml = sock_kmalloc(sk, sizeof(*iml), GFP_KERNEL);
 	if (!iml)