genetlink: fix netns vs. netlink table locking (2)
Similar to commit d136f1bd366fdb7e747ca7e0218171e7a00a98a5,
there's a bug when unregistering a generic netlink family,
which is caught by the might_sleep() added in that commit:
BUG: sleeping function called from invalid context at net/netlink/af_netlink.c:183
in_atomic(): 1, irqs_disabled(): 0, pid: 1510, name: rmmod
2 locks held by rmmod/1510:
#0: (genl_mutex){+.+.+.}, at: [<ffffffff8138283b>] genl_unregister_family+0x2b/0x130
#1: (rcu_read_lock){.+.+..}, at: [<ffffffff8138270c>] __genl_unregister_mc_group+0x1c/0x120
Pid: 1510, comm: rmmod Not tainted 2.6.31-wl #444
Call Trace:
[<ffffffff81044ff9>] __might_sleep+0x119/0x150
[<ffffffff81380501>] netlink_table_grab+0x21/0x100
[<ffffffff813813a3>] netlink_clear_multicast_users+0x23/0x60
[<ffffffff81382761>] __genl_unregister_mc_group+0x71/0x120
[<ffffffff81382866>] genl_unregister_family+0x56/0x130
[<ffffffffa0007d85>] nl80211_exit+0x15/0x20 [cfg80211]
[<ffffffffa000005a>] cfg80211_exit+0x1a/0x40 [cfg80211]
Fix in the same way by grabbing the netlink table lock
before doing rcu_read_lock().
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 080f6ba..ab5d312 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -187,6 +187,7 @@
extern void netlink_kernel_release(struct sock *sk);
extern int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);
+extern void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
extern void netlink_clear_multicast_users(struct sock *sk, unsigned int group);
extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);
extern int netlink_has_listeners(struct sock *sk, unsigned int group);
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 55180b9..a4bafbf 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1609,6 +1609,16 @@
return err;
}
+void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
+{
+ struct sock *sk;
+ struct hlist_node *node;
+ struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
+
+ sk_for_each_bound(sk, node, &tbl->mc_list)
+ netlink_update_socket_mc(nlk_sk(sk), group, 0);
+}
+
/**
* netlink_clear_multicast_users - kick off multicast listeners
*
@@ -1619,15 +1629,8 @@
*/
void netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
{
- struct sock *sk;
- struct hlist_node *node;
- struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
-
netlink_table_grab();
-
- sk_for_each_bound(sk, node, &tbl->mc_list)
- netlink_update_socket_mc(nlk_sk(sk), group, 0);
-
+ __netlink_clear_multicast_users(ksk, group);
netlink_table_ungrab();
}
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 566941e..44ff3f3 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -220,10 +220,12 @@
struct net *net;
BUG_ON(grp->family != family);
+ netlink_table_grab();
rcu_read_lock();
for_each_net_rcu(net)
- netlink_clear_multicast_users(net->genl_sock, grp->id);
+ __netlink_clear_multicast_users(net->genl_sock, grp->id);
rcu_read_unlock();
+ netlink_table_ungrab();
clear_bit(grp->id, mc_groups);
list_del(&grp->list);
