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Date: Thu, 25 Mar 2010 11:06:21 +0000
From: David Howells <dhowells@...hat.com>
To: paul.moore@...com
Cc: netdev@...r.kernel.org, David Howells <dhowells@...hat.com>
Subject: [PATCH] NETLABEL: Fix an RCU warning
Fix an RCU warning in the netlabel code due to missing rcu read locking around
an rcu_dereference() in netlbl_unlhsh_hash() when called from
netlbl_unlhsh_netdev_handler():
===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
net/netlabel/netlabel_unlabeled.c:246 invoked rcu_dereference_check() without protection!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 0
2 locks held by ip/5108:
#0: (rtnl_mutex){+.+.+.}, at: [<ffffffff812c4a36>] rtnl_lock+0x12/0x14
#1: (netlbl_unlhsh_lock){+.+...}, at: [<ffffffff8134daa4>] netlbl_unlhsh_netdev_handler+0x1e/0x86
stack backtrace:
Pid: 5108, comm: ip Not tainted 2.6.34-rc2-cachefs #114
Call Trace:
[<ffffffff8105121f>] lockdep_rcu_dereference+0xaa/0xb2
[<ffffffff8134d781>] netlbl_unlhsh_hash+0x3e/0x50
[<ffffffff8134d7a1>] netlbl_unlhsh_search_iface+0xe/0x84
[<ffffffff8134daaf>] netlbl_unlhsh_netdev_handler+0x29/0x86
[<ffffffff81048362>] notifier_call_chain+0x32/0x5e
[<ffffffff810483fe>] raw_notifier_call_chain+0xf/0x11
[<ffffffff812ba924>] call_netdevice_notifiers+0x16/0x18
[<ffffffff812bac22>] __dev_notify_flags+0x37/0x5b
[<ffffffff812bac8c>] dev_change_flags+0x46/0x52
[<ffffffff812c41af>] do_setlink+0x250/0x3cd
[<ffffffff812c4ee8>] rtnl_newlink+0x2b6/0x49d
[<ffffffff812c4cdd>] ? rtnl_newlink+0xab/0x49d
[<ffffffff812c4c17>] rtnetlink_rcv_msg+0x1b7/0x1d2
[<ffffffff812c4a60>] ? rtnetlink_rcv_msg+0x0/0x1d2
[<ffffffff812cc1dc>] netlink_rcv_skb+0x3e/0x8f
[<ffffffff812c4a59>] rtnetlink_rcv+0x21/0x28
[<ffffffff812cbefe>] netlink_unicast+0x218/0x28f
[<ffffffff812cc76e>] netlink_sendmsg+0x26b/0x27a
[<ffffffff812a9f1d>] sock_sendmsg+0xd4/0xf5
[<ffffffff81096dca>] ? might_fault+0x4e/0x9e
[<ffffffff81096dca>] ? might_fault+0x4e/0x9e
[<ffffffff81096e13>] ? might_fault+0x97/0x9e
[<ffffffff81096dca>] ? might_fault+0x4e/0x9e
[<ffffffff812b4122>] ? verify_iovec+0x59/0x97
[<ffffffff812aa1d9>] sys_sendmsg+0x209/0x273
[<ffffffff810976dc>] ? __do_fault+0x395/0x3cd
[<ffffffff8109928f>] ? handle_mm_fault+0x324/0x69d
[<ffffffff81051e4e>] ? trace_hardirqs_on_caller+0x10c/0x130
[<ffffffff81074972>] ? audit_syscall_entry+0x17d/0x1b0
[<ffffffff81364154>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff81001eeb>] system_call_fastpath+0x16/0x1b
Signed-off-by: David Howells <dhowells@...hat.com>
---
net/netlabel/netlabel_unlabeled.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
index 852d9d7..7ea64e4 100644
--- a/net/netlabel/netlabel_unlabeled.c
+++ b/net/netlabel/netlabel_unlabeled.c
@@ -799,6 +799,7 @@ static int netlbl_unlhsh_netdev_handler(struct notifier_block *this,
/* XXX - should this be a check for NETDEV_DOWN or _UNREGISTER? */
if (event == NETDEV_DOWN) {
+ rcu_read_lock();
spin_lock(&netlbl_unlhsh_lock);
iface = netlbl_unlhsh_search_iface(dev->ifindex);
if (iface != NULL && iface->valid) {
@@ -807,6 +808,7 @@ static int netlbl_unlhsh_netdev_handler(struct notifier_block *this,
} else
iface = NULL;
spin_unlock(&netlbl_unlhsh_lock);
+ rcu_read_unlock();
}
if (iface != NULL)
--
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