linux-kernel - [21/67] SELinux: Fix RCU deref check warning in sel_netport

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Date:	Tue, 03 Jan 2012 14:29:39 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, David Howells <dhowells@...hat.com>,
	Paul Moore <paul@...l-moore.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	James Morris <jmorris@...ei.org>
Subject: [21/67] SELinux: Fix RCU deref check warning in sel_netport_insert()

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@...hat.com>

commit 50345f1ea9cda4618d9c26e590a97ecd4bc7ac75 upstream.

Fix the following bug in sel_netport_insert() where rcu_dereference() should
be rcu_dereference_protected() as sel_netport_lock is held.

===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
security/selinux/netport.c:127 invoked rcu_dereference_check() without protection!

other info that might help us debug this:

rcu_scheduler_active = 1, debug_locks = 0
1 lock held by ossec-rootcheck/3323:
 #0:  (sel_netport_lock){+.....}, at: [<ffffffff8117d775>] sel_netport_sid+0xbb/0x226

stack backtrace:
Pid: 3323, comm: ossec-rootcheck Not tainted 3.1.0-rc8-fsdevel+ #1095
Call Trace:
 [<ffffffff8105cfb7>] lockdep_rcu_dereference+0xa7/0xb0
 [<ffffffff8117d871>] sel_netport_sid+0x1b7/0x226
 [<ffffffff8117d6ba>] ? sel_netport_avc_callback+0xbc/0xbc
 [<ffffffff8117556c>] selinux_socket_bind+0x115/0x230
 [<ffffffff810a5388>] ? might_fault+0x4e/0x9e
 [<ffffffff810a53d1>] ? might_fault+0x97/0x9e
 [<ffffffff81171cf4>] security_socket_bind+0x11/0x13
 [<ffffffff812ba967>] sys_bind+0x56/0x95
 [<ffffffff81380dac>] ? sysret_check+0x27/0x62
 [<ffffffff8105b767>] ? trace_hardirqs_on_caller+0x11e/0x155
 [<ffffffff81076fcd>] ? audit_syscall_entry+0x17b/0x1ae
 [<ffffffff811b5eae>] ? trace_hardirqs_on_thunk+0x3a/0x3f
 [<ffffffff81380d7b>] system_call_fastpath+0x16/0x1b

Signed-off-by: David Howells <dhowells@...hat.com>
Acked-by: Paul Moore <paul@...l-moore.com>
Acked-by: Eric Dumazet <eric.dumazet@...il.com>
Signed-off-by: James Morris <jmorris@...ei.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 security/selinux/netport.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/security/selinux/netport.c
+++ b/security/selinux/netport.c
@@ -139,7 +139,9 @@ static void sel_netport_insert(struct se
 	if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
 		struct sel_netport *tail;
 		tail = list_entry(
-			rcu_dereference(sel_netport_hash[idx].list.prev),
+			rcu_dereference_protected(
+				sel_netport_hash[idx].list.prev,
+				lockdep_is_held(&sel_netport_lock)),
 			struct sel_netport, list);
 		list_del_rcu(&tail->list);
 		call_rcu(&tail->rcu, sel_netport_free);


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