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netfilter: unlock xt_table earlier in __do_replace 

Now it's doing cleanup_entry for oldinfo under the xt_table lock,
but it's not really necessary. After the replacement job is done
in xt_replace_table, oldinfo is not used elsewhere any more, and
it can be freed without xt_table lock safely.

The important thing is that rtnl_lock is called in some xt_target
destroy, which means rtnl_lock, a big lock is used in xt_table
lock, a smaller one. It usually could be the reason why a dead
lock may happen.

Besides, all xt_target/match checkentry is called out of xt_table
lock. It's better also to move all cleanup_entry calling out of
xt_table lock, just as do_replace_finish does for ebtables.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Xin Long 2018-02-16 18:04:56 +08:00 committed by Pablo Neira Ayuso
parent 2db3fec507
commit f31e5f1a89
3 changed files with 6 additions and 3 deletions
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3
net/ipv4/netfilter/arp_tables.c
View File

@ -925,6 +925,8 @@ static int __do_replace(struct net *net, const char *name,
(newinfo->number <= oldinfo->initial_entries))
module_put(t->me);
xt_table_unlock(t);
get_old_counters(oldinfo, counters);
/* Decrease module usage counts and free resource */
@ -939,7 +941,6 @@ static int __do_replace(struct net *net, const char *name,
net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n");
}
vfree(counters);
xt_table_unlock(t);
return ret;
put_module:

3
net/ipv4/netfilter/ip_tables.c
View File

@ -1087,6 +1087,8 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
(newinfo->number <= oldinfo->initial_entries))
module_put(t->me);
xt_table_unlock(t);
get_old_counters(oldinfo, counters);
/* Decrease module usage counts and free resource */
@ -1100,7 +1102,6 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
net_warn_ratelimited("iptables: counters copy to user failed while replacing table\n");
}
vfree(counters);
xt_table_unlock(t);
return ret;
put_module:

3
net/ipv6/netfilter/ip6_tables.c
View File

@ -1105,6 +1105,8 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
(newinfo->number <= oldinfo->initial_entries))
module_put(t->me);
xt_table_unlock(t);
get_old_counters(oldinfo, counters);
/* Decrease module usage counts and free resource */
@ -1118,7 +1120,6 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
net_warn_ratelimited("ip6tables: counters copy to user failed while replacing table\n");
}
vfree(counters);
xt_table_unlock(t);
return ret;
put_module: