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Commit ed86308f authored by Patrick McHardy's avatar Patrick McHardy
Browse files

netfilter: remove invalid rcu_dereference() calls 



The CONFIG_PROVE_RCU option discovered a few invalid uses of
rcu_dereference() in netfilter. In all these cases, the code code
intends to check whether a pointer is already assigned when
performing registration or whether the assigned pointer matches
when performing unregistration. The entire registration/
unregistration is protected by a mutex, so we don't need the
rcu_dereference() calls.

Reported-by: default avatarValdis Kletnieks <Valdis.Kletnieks@vt.edu>
Tested-by: default avatarValdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
parent e9f13cab

net/netfilter/nf_conntrack_ecache.c

+4 −14
Original line number Diff line number Diff line
@@ -81,11 +81,9 @@ EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events); 
int nf_conntrack_register_notifier(struct nf_ct_event_notifier *new)

{

	int ret = 0;

	struct nf_ct_event_notifier *notify;



	mutex_lock(&nf_ct_ecache_mutex);

	notify = rcu_dereference(nf_conntrack_event_cb);

	if (notify != NULL) {

	if (nf_conntrack_event_cb != NULL) {

		ret = -EBUSY;

		goto out_unlock;

	}
@@ -101,11 +99,8 @@ EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier); 


void nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *new)

{

	struct nf_ct_event_notifier *notify;



	mutex_lock(&nf_ct_ecache_mutex);

	notify = rcu_dereference(nf_conntrack_event_cb);

	BUG_ON(notify != new);

	BUG_ON(nf_conntrack_event_cb != new);

	rcu_assign_pointer(nf_conntrack_event_cb, NULL);

	mutex_unlock(&nf_ct_ecache_mutex);

}
@@ -114,11 +109,9 @@ EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier); 
int nf_ct_expect_register_notifier(struct nf_exp_event_notifier *new)

{

	int ret = 0;

	struct nf_exp_event_notifier *notify;



	mutex_lock(&nf_ct_ecache_mutex);

	notify = rcu_dereference(nf_expect_event_cb);

	if (notify != NULL) {

	if (nf_expect_event_cb != NULL) {

		ret = -EBUSY;

		goto out_unlock;

	}
@@ -134,11 +127,8 @@ EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier); 


void nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *new)

{

	struct nf_exp_event_notifier *notify;



	mutex_lock(&nf_ct_ecache_mutex);

	notify = rcu_dereference(nf_expect_event_cb);

	BUG_ON(notify != new);

	BUG_ON(nf_expect_event_cb != new);

	rcu_assign_pointer(nf_expect_event_cb, NULL);

	mutex_unlock(&nf_ct_ecache_mutex);

}

net/netfilter/nf_log.c

+2 −6
Original line number Diff line number Diff line
@@ -35,7 +35,6 @@ static struct nf_logger *__find_logger(int pf, const char *str_logger) 
/* return EEXIST if the same logger is registred, 0 on success. */

int nf_log_register(u_int8_t pf, struct nf_logger *logger)

{

	const struct nf_logger *llog;

	int i;



	if (pf >= ARRAY_SIZE(nf_loggers))
@@ -52,8 +51,7 @@ int nf_log_register(u_int8_t pf, struct nf_logger *logger) 
	} else {

		/* register at end of list to honor first register win */

		list_add_tail(&logger->list[pf], &nf_loggers_l[pf]);

		llog = rcu_dereference(nf_loggers[pf]);

		if (llog == NULL)

		if (nf_loggers[pf] == NULL)

			rcu_assign_pointer(nf_loggers[pf], logger);

	}
@@ -65,13 +63,11 @@ EXPORT_SYMBOL(nf_log_register); 


void nf_log_unregister(struct nf_logger *logger)

{

	const struct nf_logger *c_logger;

	int i;



	mutex_lock(&nf_log_mutex);

	for (i = 0; i < ARRAY_SIZE(nf_loggers); i++) {

		c_logger = rcu_dereference(nf_loggers[i]);

		if (c_logger == logger)

		if (nf_loggers[i] == logger)

			rcu_assign_pointer(nf_loggers[i], NULL);

		list_del(&logger->list[i]);

	}