linux-kernel - [PATCH 3.2 44/77] ipv4: igmp: Allow removing groups from a removed interface

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 24 Dec 2015 15:37:42 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "David S. Miller" <davem@...emloft.net>,
	"Andrew Lunn" <andrew@...n.ch>
Subject: [PATCH 3.2 44/77] ipv4: igmp: Allow removing groups from a
 removed interface

3.2.75-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andrew Lunn <andrew@...n.ch>

commit 4eba7bb1d72d9bde67d810d09bf62dc207b63c5c upstream.

When a multicast group is joined on a socket, a struct ip_mc_socklist
is appended to the sockets mc_list containing information about the
joined group.

If the interface is hot unplugged, this entry becomes stale. Prior to
commit 52ad353a5344f ("igmp: fix the problem when mc leave group") it
was possible to remove the stale entry by performing a
IP_DROP_MEMBERSHIP, passing either the old ifindex or ip address on
the interface. However, this fix enforces that the interface must
still exist. Thus with time, the number of stale entries grows, until
sysctl_igmp_max_memberships is reached and then it is not possible to
join and more groups.

The previous patch fixes an issue where a IP_DROP_MEMBERSHIP is
performed without specifying the interface, either by ifindex or ip
address. However here we do supply one of these. So loosen the
restriction on device existence to only apply when the interface has
not been specified. This then restores the ability to clean up the
stale entries.

Signed-off-by: Andrew Lunn <andrew@...n.ch>
Fixes: 52ad353a5344f "(igmp: fix the problem when mc leave group")
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/ipv4/igmp.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -1866,7 +1866,7 @@ int ip_mc_leave_group(struct sock *sk, s

 	rtnl_lock();
 	in_dev = ip_mc_find_dev(net, imr);
-	if (!in_dev) {
+	if (!imr->imr_ifindex && !imr->imr_address.s_addr && !in_dev) {
 		ret = -ENODEV;
 		goto out;
 	}
@@ -1887,7 +1887,8 @@ int ip_mc_leave_group(struct sock *sk, s

 		*imlp = iml->next_rcu;

-		ip_mc_dec_group(in_dev, group);
+		if (in_dev)
+			ip_mc_dec_group(in_dev, group);
 		rtnl_unlock();
 		/* decrease mem now to avoid the memleak warning */
 		atomic_sub(sizeof(*iml), &sk->sk_omem_alloc);

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/