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authorLiping Zhang <zlpnobody@gmail.com>2017-03-25 08:53:12 +0800
committerPablo Neira Ayuso <pablo@netfilter.org>2017-03-27 13:47:28 +0200
commit3b7dabf029478bb80507a6c4500ca94132a2bc0b (patch)
tree7fdc91ed3c571753fbaffaef9e520882925e1703 /net
parentf83bf8da1135ca635aac8f062cad3f001fcf3a26 (diff)
downloadlinux-3b7dabf029478bb80507a6c4500ca94132a2bc0b.tar.bz2
netfilter: invoke synchronize_rcu after set the _hook_ to NULL
Otherwise, another CPU may access the invalid pointer. For example: CPU0 CPU1 - rcu_read_lock(); - pfunc = _hook_; _hook_ = NULL; - mod unload - - pfunc(); // invalid, panic - rcu_read_unlock(); So we must call synchronize_rcu() to wait the rcu reader to finish. Also note, in nf_nat_snmp_basic_fini, synchronize_rcu() will be invoked by later nf_conntrack_helper_unregister, but I'm inclined to add a explicit synchronize_rcu after set the nf_nat_snmp_hook to NULL. Depend on such obscure assumptions is not a good idea. Last, in nfnetlink_cttimeout, we use kfree_rcu to free the time object, so in cttimeout_exit, invoking rcu_barrier() is not necessary at all, remove it too. Signed-off-by: Liping Zhang <zlpnobody@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/netfilter/nf_nat_snmp_basic.c1
-rw-r--r--net/netfilter/nf_conntrack_ecache.c2
-rw-r--r--net/netfilter/nf_conntrack_netlink.c1
-rw-r--r--net/netfilter/nf_nat_core.c2
-rw-r--r--net/netfilter/nfnetlink_cttimeout.c2
5 files changed, 7 insertions, 1 deletions
diff --git a/net/ipv4/netfilter/nf_nat_snmp_basic.c b/net/ipv4/netfilter/nf_nat_snmp_basic.c
index c9b52c361da2..5a8f7c360887 100644
--- a/net/ipv4/netfilter/nf_nat_snmp_basic.c
+++ b/net/ipv4/netfilter/nf_nat_snmp_basic.c
@@ -1304,6 +1304,7 @@ static int __init nf_nat_snmp_basic_init(void)
static void __exit nf_nat_snmp_basic_fini(void)
{
RCU_INIT_POINTER(nf_nat_snmp_hook, NULL);
+ synchronize_rcu();
nf_conntrack_helper_unregister(&snmp_trap_helper);
}
diff --git a/net/netfilter/nf_conntrack_ecache.c b/net/netfilter/nf_conntrack_ecache.c
index da9df2d56e66..22fc32143e9c 100644
--- a/net/netfilter/nf_conntrack_ecache.c
+++ b/net/netfilter/nf_conntrack_ecache.c
@@ -290,6 +290,7 @@ void nf_conntrack_unregister_notifier(struct net *net,
BUG_ON(notify != new);
RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL);
mutex_unlock(&nf_ct_ecache_mutex);
+ /* synchronize_rcu() is called from ctnetlink_exit. */
}
EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
@@ -326,6 +327,7 @@ void nf_ct_expect_unregister_notifier(struct net *net,
BUG_ON(notify != new);
RCU_INIT_POINTER(net->ct.nf_expect_event_cb, NULL);
mutex_unlock(&nf_ct_ecache_mutex);
+ /* synchronize_rcu() is called from ctnetlink_exit. */
}
EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 6806b5e73567..908d858034e4 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -3442,6 +3442,7 @@ static void __exit ctnetlink_exit(void)
#ifdef CONFIG_NETFILTER_NETLINK_GLUE_CT
RCU_INIT_POINTER(nfnl_ct_hook, NULL);
#endif
+ synchronize_rcu();
}
module_init(ctnetlink_init);
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index 94b14c5a8b17..82802e4a6640 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -903,6 +903,8 @@ static void __exit nf_nat_cleanup(void)
#ifdef CONFIG_XFRM
RCU_INIT_POINTER(nf_nat_decode_session_hook, NULL);
#endif
+ synchronize_rcu();
+
for (i = 0; i < NFPROTO_NUMPROTO; i++)
kfree(nf_nat_l4protos[i]);
diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c
index 139e0867e56e..47d6656c9119 100644
--- a/net/netfilter/nfnetlink_cttimeout.c
+++ b/net/netfilter/nfnetlink_cttimeout.c
@@ -646,8 +646,8 @@ static void __exit cttimeout_exit(void)
#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, NULL);
RCU_INIT_POINTER(nf_ct_timeout_put_hook, NULL);
+ synchronize_rcu();
#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
- rcu_barrier();
}
module_init(cttimeout_init);