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    Subject[PATCH 4.19 18/62] igmp: Fix a data-race around sysctl_igmp_max_memberships.
    Date
    From: Kuniyuki Iwashima <kuniyu@amazon.com>

    [ Upstream commit 6305d821e3b9b5379d348528e5b5faf316383bc2 ]

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

    diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
    index 957e1170a8a3..b831825f234f 100644
    --- a/net/ipv4/igmp.c
    +++ b/net/ipv4/igmp.c
    @@ -2212,7 +2212,7 @@ 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)
    --
    2.35.1


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