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Commit be120ad8 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Greg Kroah-Hartman
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igmp: Fix a data-race around sysctl_igmp_max_memberships. 



[ 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: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent a84b4afa

net/ipv4/igmp.c

+1 −1
Original line number Diff line number Diff line
@@ -2171,7 +2171,7 @@ 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)