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Message-Id: <1262724742-5232-1-git-send-email-fleitner@redhat.com>
Date: Tue, 5 Jan 2010 18:52:22 -0200
From: Flavio Leitner <fleitner@...hat.com>
To: netdev@...r.kernel.org
Cc: David Miller <davem@...emloft.net>,
David Stevens <dlstevens@...ibm.com>,
Eric Dumazet <eric.dumazet@...il.com>,
Flavio Leitner <fleitner@...hat.com>
Subject: [PATCH] igmp: fix ip_mc_sf_allow race [v3]
Almost all igmp functions accessing inet->mc_list are protected by
rtnl_lock(), but there is one exception which is ip_mc_sf_allow(),
so there is a chance of either ip_mc_drop_socket or ip_mc_leave_group
remove an entry while ip_mc_sf_allow is running causing a crash.
Signed-off-by: Flavio Leitner <fleitner@...hat.com>
---
include/linux/igmp.h | 1 +
net/ipv4/igmp.c | 58 +++++++++++++++++++++++++++++++++++++------------
2 files changed, 45 insertions(+), 14 deletions(-)
diff --git a/include/linux/igmp.h b/include/linux/igmp.h
index 724c27e..9cccd16 100644
--- a/include/linux/igmp.h
+++ b/include/linux/igmp.h
@@ -170,6 +170,7 @@ struct ip_mc_socklist {
struct ip_mreqn multi;
unsigned int sfmode; /* MCAST_{INCLUDE,EXCLUDE} */
struct ip_sf_socklist *sflist;
+ struct rcu_head rcu;
};
struct ip_sf_list {
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 76c0840..61ff685 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -1799,7 +1799,7 @@ int ip_mc_join_group(struct sock *sk , struct ip_mreqn *imr)
iml->next = inet->mc_list;
iml->sflist = NULL;
iml->sfmode = MCAST_EXCLUDE;
- inet->mc_list = iml;
+ rcu_assign_pointer(inet->mc_list, iml);
ip_mc_inc_group(in_dev, addr);
err = 0;
done:
@@ -1825,6 +1825,17 @@ static int ip_mc_leave_src(struct sock *sk, struct ip_mc_socklist *iml,
return err;
}
+
+static void ip_mc_socklist_reclaim(struct rcu_head *rp)
+{
+ struct ip_mc_socklist *iml;
+
+ iml = container_of(rp, struct ip_mc_socklist, rcu);
+ /* sk_omem_alloc should have been decreased by the caller*/
+ kfree(iml);
+}
+
+
/*
* Ask a socket to leave a group.
*/
@@ -1854,12 +1865,15 @@ int ip_mc_leave_group(struct sock *sk, struct ip_mreqn *imr)
(void) ip_mc_leave_src(sk, iml, in_dev);
- *imlp = iml->next;
+ rcu_assign_pointer(*imlp, iml->next);
if (in_dev)
ip_mc_dec_group(in_dev, group);
+
rtnl_unlock();
- sock_kfree_s(sk, iml, sizeof(*iml));
+ /* decrease mem now to avoid the memleak warning */
+ atomic_sub(sizeof(*iml), &sk->sk_omem_alloc);
+ call_rcu(&iml->rcu, ip_mc_socklist_reclaim);
return 0;
}
if (!in_dev)
@@ -2209,30 +2223,40 @@ int ip_mc_sf_allow(struct sock *sk, __be32 loc_addr, __be32 rmt_addr, int dif)
struct ip_mc_socklist *pmc;
struct ip_sf_socklist *psl;
int i;
+ int ret;
+ ret = 1;
if (!ipv4_is_multicast(loc_addr))
- return 1;
+ goto out;
- for (pmc=inet->mc_list; pmc; pmc=pmc->next) {
+ rcu_read_lock();
+ for (pmc=rcu_dereference(inet->mc_list); pmc; pmc=rcu_dereference(pmc->next)) {
if (pmc->multi.imr_multiaddr.s_addr == loc_addr &&
pmc->multi.imr_ifindex == dif)
break;
}
+ ret = inet->mc_all;
if (!pmc)
- return inet->mc_all;
+ goto unlock;
psl = pmc->sflist;
+ ret = (pmc->sfmode == MCAST_EXCLUDE);
if (!psl)
- return pmc->sfmode == MCAST_EXCLUDE;
+ goto unlock;
for (i=0; i<psl->sl_count; i++) {
if (psl->sl_addr[i] == rmt_addr)
break;
}
+ ret = 0;
if (pmc->sfmode == MCAST_INCLUDE && i >= psl->sl_count)
- return 0;
+ goto unlock;
if (pmc->sfmode == MCAST_EXCLUDE && i < psl->sl_count)
- return 0;
- return 1;
+ goto unlock;
+ ret = 1;
+unlock:
+ rcu_read_unlock();
+out:
+ return ret;
}
/*
@@ -2245,13 +2269,17 @@ void ip_mc_drop_socket(struct sock *sk)
struct ip_mc_socklist *iml;
struct net *net = sock_net(sk);
- if (inet->mc_list == NULL)
+ rcu_read_lock();
+ if (rcu_dereference(inet->mc_list) == NULL) {
+ rcu_read_unlock();
return;
+ }
+ rcu_read_unlock();
rtnl_lock();
- while ((iml = inet->mc_list) != NULL) {
+ while ((iml = rcu_dereference(inet->mc_list)) != NULL) {
struct in_device *in_dev;
- inet->mc_list = iml->next;
+ rcu_assign_pointer(inet->mc_list, iml->next);
in_dev = inetdev_by_index(net, iml->multi.imr_ifindex);
(void) ip_mc_leave_src(sk, iml, in_dev);
@@ -2259,7 +2287,9 @@ void ip_mc_drop_socket(struct sock *sk)
ip_mc_dec_group(in_dev, iml->multi.imr_multiaddr.s_addr);
in_dev_put(in_dev);
}
- sock_kfree_s(sk, iml, sizeof(*iml));
+ /* decrease mem now to avoid the memleak warning */
+ atomic_sub(sizeof(*iml), &sk->sk_omem_alloc);
+ call_rcu(&iml->rcu, ip_mc_socklist_reclaim);
}
rtnl_unlock();
}
--
1.6.2.3
--
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