ipv4: Fix a data-race around sysctl_fib_sync_mem.

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>

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 2734c3af7e2454fe8d57f5171071ae5afe795eda..46e8a5125853aeb95c97252e65be94a185b52c3d 100644 (file)
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -498,7 +498,7 @@ 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();
        }