linux-kernel - [PATCH ipsec] xfrm: policy: init locks early

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Date:   Wed,  8 Feb 2017 11:52:29 +0100
From:   Florian Westphal <fw@...len.de>
To:     <netdev@...r.kernel.org>
Cc:     dvyukov@...gle.com, steffen.klassert@...unet.com,
        linux-kernel@...r.kernel.org, Florian Westphal <fw@...len.de>
Subject: [PATCH ipsec] xfrm: policy: init locks early

Dmitry reports following splat:
 INFO: trying to register non-static key.
 the code is fine but needs lockdep annotation.
 turning off the locking correctness validator.
 CPU: 0 PID: 13059 Comm: syz-executor1 Not tainted 4.10.0-rc7-next-20170207 #1
[..]
 spin_lock_bh include/linux/spinlock.h:304 [inline]
 xfrm_policy_flush+0x32/0x470 net/xfrm/xfrm_policy.c:963
 xfrm_policy_fini+0xbf/0x560 net/xfrm/xfrm_policy.c:3041
 xfrm_net_init+0x79f/0x9e0 net/xfrm/xfrm_policy.c:3091
 ops_init+0x10a/0x530 net/core/net_namespace.c:115
 setup_net+0x2ed/0x690 net/core/net_namespace.c:291
 copy_net_ns+0x26c/0x530 net/core/net_namespace.c:396
 create_new_namespaces+0x409/0x860 kernel/nsproxy.c:106
 unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:205
 SYSC_unshare kernel/fork.c:2281 [inline]

Problem is that when we get error during xfrm_net_init we will call
xfrm_policy_fini which will acquire xfrm_policy_lock before it was
initialized.  Just move it around so locks get set up first.

Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Fixes: 283bc9f35bbbcb0e9 ("xfrm: Namespacify xfrm state/policy locks")
Signed-off-by: Florian Westphal <fw@...len.de>
---
 net/xfrm/xfrm_policy.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 177e208e8ff5..3c8f5b70abf8 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3062,6 +3062,11 @@ static int __net_init xfrm_net_init(struct net *net)
 {
 	int rv;

+	/* Initialize the per-net locks here */
+	spin_lock_init(&net->xfrm.xfrm_state_lock);
+	spin_lock_init(&net->xfrm.xfrm_policy_lock);
+	mutex_init(&net->xfrm.xfrm_cfg_mutex);
+
 	rv = xfrm_statistics_init(net);
 	if (rv < 0)
 		goto out_statistics;
@@ -3078,11 +3083,6 @@ static int __net_init xfrm_net_init(struct net *net)
 	if (rv < 0)
 		goto out;

-	/* Initialize the per-net locks here */
-	spin_lock_init(&net->xfrm.xfrm_state_lock);
-	spin_lock_init(&net->xfrm.xfrm_policy_lock);
-	mutex_init(&net->xfrm.xfrm_cfg_mutex);
-
 	return 0;

 out:
-- 
2.10.2