This is a note to let you know that I've just added the patch titled
netfilter: ipt_CLUSTERIP: fix a race condition of proc file creation
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netfilter-ipt_clusterip-fix-a-race-condition-of-proc-file-creation.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b3e456fce9f51d6276e576d00271e2813c1b8b67 Mon Sep 17 00:00:00 2001
From: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Date: Wed, 7 Feb 2018 21:59:17 -0800
Subject: netfilter: ipt_CLUSTERIP: fix a race condition of proc file creation
From: Cong Wang <xiyou.wangcong@xxxxxxxxx>
commit b3e456fce9f51d6276e576d00271e2813c1b8b67 upstream.
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@xxxxxxxxxxxxxxxxxxxxxxxxx>
Fixes: 6c5d5cfbe3c5 ("netfilter: ipt_CLUSTERIP: check duplicate config when initializing")
Tested-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Cc: Xin Long <lucien.xin@xxxxxxxxx>
Cc: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Reviewed-by: Xin Long <lucien.xin@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/netfilter/ipt_CLUSTERIP.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -107,12 +107,6 @@ clusterip_config_entry_put(struct net *n
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 *n
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();
Patches currently in stable-queue which might be from xiyou.wangcong@xxxxxxxxx are
queue-4.14/netfilter-ipt_clusterip-fix-a-race-condition-of-proc-file-creation.patch