SELinux: Fix RCU deref check warning in sel_netport_insert()

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@redhat.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: stable@kernel.org
Signed-off-by: James Morris <jmorris@namei.org>

diff --git a/security/selinux/netport.c b/security/selinux/netport.c
index 0b62bd112461c712cfc9425f9e8ac0f6caf194f0..7b9eb1faf68b5fe435b7f70e36ff21330934d6a2 100644 (file)
--- a/security/selinux/netport.c
+++ b/security/selinux/netport.c
@@ -123,7 +123,9 @@ static void sel_netport_insert(struct sel_netport *port)
        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);
                kfree_rcu(tail, rcu);