[PATCH 5.15 062/167] ipv4: Fix a data-race around sysctl_fib_sync_mem.

Greg Kroah-Hartman
2022-07-19T12:36:06Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ 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>
---
net/ipv4/fib_trie.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index f7f74d5c14da..a9cd9c2bd84e 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();
}
--
2.35.1