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Commit ed876e99 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Greg Kroah-Hartman
Browse files

igmp: Fix data-races around sysctl_igmp_llm_reports. 



[ Upstream commit f6da2267e71106474fbc0943dc24928b9cb79119 ]

While reading sysctl_igmp_llm_reports, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

This test can be packed into a helper, so such changes will be in the
follow-up series after net is merged into net-next.

  if (ipv4_is_local_multicast(pmc->multiaddr) &&
      !READ_ONCE(net->ipv4.sysctl_igmp_llm_reports))

Fixes: df2cf4a7 ("IGMP: Inhibit reports for local multicast groups")
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 52d3c2e6

net/ipv4/igmp.c

+13 −8
Original line number Original line Diff line number Diff line
@@ -471,7 +471,8 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ip_mc_list *pmc, 




	if (pmc->multiaddr == IGMP_ALL_HOSTS)

	if (pmc->multiaddr == IGMP_ALL_HOSTS)

		return skb;

		return skb;

	if (ipv4_is_local_multicast(pmc->multiaddr) && !net->ipv4.sysctl_igmp_llm_reports)

	if (ipv4_is_local_multicast(pmc->multiaddr) &&

	    !READ_ONCE(net->ipv4.sysctl_igmp_llm_reports))

		return skb;

		return skb;





	mtu = READ_ONCE(dev->mtu);

	mtu = READ_ONCE(dev->mtu);
@@ -597,7 +598,7 @@ static int igmpv3_send_report(struct in_device *in_dev, struct ip_mc_list *pmc) 
			if (pmc->multiaddr == IGMP_ALL_HOSTS)

			if (pmc->multiaddr == IGMP_ALL_HOSTS)

				continue;

				continue;

			if (ipv4_is_local_multicast(pmc->multiaddr) &&

			if (ipv4_is_local_multicast(pmc->multiaddr) &&

			     !net->ipv4.sysctl_igmp_llm_reports)

			    !READ_ONCE(net->ipv4.sysctl_igmp_llm_reports))

				continue;

				continue;

			spin_lock_bh(&pmc->lock);

			spin_lock_bh(&pmc->lock);

			if (pmc->sfcount[MCAST_EXCLUDE])

			if (pmc->sfcount[MCAST_EXCLUDE])
@@ -740,7 +741,8 @@ static int igmp_send_report(struct in_device *in_dev, struct ip_mc_list *pmc, 
	if (type == IGMPV3_HOST_MEMBERSHIP_REPORT)

	if (type == IGMPV3_HOST_MEMBERSHIP_REPORT)

		return igmpv3_send_report(in_dev, pmc);

		return igmpv3_send_report(in_dev, pmc);





	if (ipv4_is_local_multicast(group) && !net->ipv4.sysctl_igmp_llm_reports)

	if (ipv4_is_local_multicast(group) &&

	    !READ_ONCE(net->ipv4.sysctl_igmp_llm_reports))

		return 0;

		return 0;





	if (type == IGMP_HOST_LEAVE_MESSAGE)

	if (type == IGMP_HOST_LEAVE_MESSAGE)
@@ -924,7 +926,8 @@ static bool igmp_heard_report(struct in_device *in_dev, __be32 group) 




	if (group == IGMP_ALL_HOSTS)

	if (group == IGMP_ALL_HOSTS)

		return false;

		return false;

	if (ipv4_is_local_multicast(group) && !net->ipv4.sysctl_igmp_llm_reports)

	if (ipv4_is_local_multicast(group) &&

	    !READ_ONCE(net->ipv4.sysctl_igmp_llm_reports))

		return false;

		return false;





	rcu_read_lock();

	rcu_read_lock();
@@ -1049,7 +1052,7 @@ static bool igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb, 
		if (im->multiaddr == IGMP_ALL_HOSTS)

		if (im->multiaddr == IGMP_ALL_HOSTS)

			continue;

			continue;

		if (ipv4_is_local_multicast(im->multiaddr) &&

		if (ipv4_is_local_multicast(im->multiaddr) &&

		    !net->ipv4.sysctl_igmp_llm_reports)

		    !READ_ONCE(net->ipv4.sysctl_igmp_llm_reports))

			continue;

			continue;

		spin_lock_bh(&im->lock);

		spin_lock_bh(&im->lock);

		if (im->tm_running)

		if (im->tm_running)
@@ -1299,7 +1302,8 @@ static void igmp_group_dropped(struct ip_mc_list *im) 
#ifdef CONFIG_IP_MULTICAST

#ifdef CONFIG_IP_MULTICAST

	if (im->multiaddr == IGMP_ALL_HOSTS)

	if (im->multiaddr == IGMP_ALL_HOSTS)

		return;

		return;

	if (ipv4_is_local_multicast(im->multiaddr) && !net->ipv4.sysctl_igmp_llm_reports)

	if (ipv4_is_local_multicast(im->multiaddr) &&

	    !READ_ONCE(net->ipv4.sysctl_igmp_llm_reports))

		return;

		return;





	reporter = im->reporter;

	reporter = im->reporter;
@@ -1336,7 +1340,8 @@ static void igmp_group_added(struct ip_mc_list *im) 
#ifdef CONFIG_IP_MULTICAST

#ifdef CONFIG_IP_MULTICAST

	if (im->multiaddr == IGMP_ALL_HOSTS)

	if (im->multiaddr == IGMP_ALL_HOSTS)

		return;

		return;

	if (ipv4_is_local_multicast(im->multiaddr) && !net->ipv4.sysctl_igmp_llm_reports)

	if (ipv4_is_local_multicast(im->multiaddr) &&

	    !READ_ONCE(net->ipv4.sysctl_igmp_llm_reports))

		return;

		return;





	if (in_dev->dead)

	if (in_dev->dead)
@@ -1657,7 +1662,7 @@ static void ip_mc_rejoin_groups(struct in_device *in_dev) 
		if (im->multiaddr == IGMP_ALL_HOSTS)

		if (im->multiaddr == IGMP_ALL_HOSTS)

			continue;

			continue;

		if (ipv4_is_local_multicast(im->multiaddr) &&

		if (ipv4_is_local_multicast(im->multiaddr) &&

		    !net->ipv4.sysctl_igmp_llm_reports)

		    !READ_ONCE(net->ipv4.sysctl_igmp_llm_reports))

			continue;

			continue;





		/* a failover is happening and switches

		/* a failover is happening and switches