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


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