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authorCong Wang <xiyou.wangcong@gmail.com>2018-02-07 21:59:17 -0800
committerPablo Neira Ayuso <pablo@netfilter.org>2018-02-08 13:54:20 +0100
commitb3e456fce9f51d6276e576d00271e2813c1b8b67 (patch)
treebf1504e9cf6429f33ab2be0381f975d5caf27c42 /net
parentfd2c19b2a28bb574b3914466a68ef830212d5cf7 (diff)
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netfilter: ipt_CLUSTERIP: fix a race condition of proc file creation
There is a race condition between clusterip_config_entry_put() and clusterip_config_init(), after we release the spinlock in clusterip_config_entry_put(), a new proc file with a same IP could be created immediately since it is already removed from the configs list, therefore it triggers this warning: ------------[ cut here ]------------ proc_dir_entry 'ipt_CLUSTERIP/172.20.0.170' already registered WARNING: CPU: 1 PID: 4152 at fs/proc/generic.c:330 proc_register+0x2a4/0x370 fs/proc/generic.c:329 Kernel panic - not syncing: panic_on_warn set ... As a quick fix, just move the proc_remove() inside the spinlock. Reported-by: <syzbot+03218bcdba6aa76441a3@syzkaller.appspotmail.com> Fixes: 6c5d5cfbe3c5 ("netfilter: ipt_CLUSTERIP: check duplicate config when initializing") Tested-by: Paolo Abeni <pabeni@redhat.com> Cc: Xin Long <lucien.xin@gmail.com> Cc: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Reviewed-by: Xin Long <lucien.xin@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/netfilter/ipt_CLUSTERIP.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index 3a84a60f6b39..1ff72b87a066 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -107,12 +107,6 @@ clusterip_config_entry_put(struct net *net, struct clusterip_config *c)
local_bh_disable();
if (refcount_dec_and_lock(&c->entries, &cn->lock)) {
- list_del_rcu(&c->list);
- spin_unlock(&cn->lock);
- local_bh_enable();
-
- unregister_netdevice_notifier(&c->notifier);
-
/* In case anyone still accesses the file, the open/close
* functions are also incrementing the refcount on their own,
* so it's safe to remove the entry even if it's in use. */
@@ -120,6 +114,12 @@ clusterip_config_entry_put(struct net *net, struct clusterip_config *c)
if (cn->procdir)
proc_remove(c->pde);
#endif
+ list_del_rcu(&c->list);
+ spin_unlock(&cn->lock);
+ local_bh_enable();
+
+ unregister_netdevice_notifier(&c->notifier);
+
return;
}
local_bh_enable();