From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed, 6 Jul 2022 23:40:03 +0000 (-0700)
Subject: ipv4: Fix a data-race around sysctl_fib_sync_mem.
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=9be8aac91960ea32fd0e874758c9afee665c57d2;p=linux.git

ipv4: Fix a data-race around sysctl_fib_sync_mem.

[ Upstream commit 73318c4b7dbd0e781aaababff17376b2894745c0 ]

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

Fixes: 9ab948a91b2c ("ipv4: Allow amount of dirty memory from fib resizing to be controllable")
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/fib_trie.c b/net/ipv4/fib_trie.c
index f7f74d5c14da6..a9cd9c2bd84eb 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -497,7 +497,7 @@ static void tnode_free(struct key_vector *tn)
 		tn = container_of(head, struct tnode, rcu)->kv;
 	}
 
-	if (tnode_free_size >= sysctl_fib_sync_mem) {
+	if (tnode_free_size >= READ_ONCE(sysctl_fib_sync_mem)) {
 		tnode_free_size = 0;
 		synchronize_rcu();
 	}