Patchwork [3.5.y.z,extended,stable] Patch "selinux: fix sel_netnode_insert() suspicious rcu dereference" has been added to staging queue

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Submitter Herton Ronaldo Krzesinski
Date Dec. 10, 2012, 2:19 p.m.
Message ID <1355149187-9200-1-git-send-email-herton.krzesinski@canonical.com>
Download mbox | patch
Permalink /patch/204915/
State New
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Comments

Herton Ronaldo Krzesinski - Dec. 10, 2012, 2:19 p.m.
This is a note to let you know that I have just added a patch titled

    selinux: fix sel_netnode_insert() suspicious rcu dereference

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

From 29402ab1fe7ae23dbf70c7f24547056ddc4f2c46 Mon Sep 17 00:00:00 2001
From: Dave Jones <davej@redhat.com>
Date: Thu, 8 Nov 2012 16:09:27 -0800
Subject: [PATCH] selinux: fix sel_netnode_insert() suspicious rcu dereference

commit 88a693b5c1287be4da937699cb82068ce9db0135 upstream.

--
1.7.9.5

Patch

===============================
[ INFO: suspicious RCU usage. ]
3.5.0-rc1+ #63 Not tainted
-------------------------------
security/selinux/netnode.c:178 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

rcu_scheduler_active = 1, debug_locks = 0
1 lock held by trinity-child1/8750:
 #0:  (sel_netnode_lock){+.....}, at: [<ffffffff812d8f8a>] sel_netnode_sid+0x16a/0x3e0

stack backtrace:
Pid: 8750, comm: trinity-child1 Not tainted 3.5.0-rc1+ #63
Call Trace:
 [<ffffffff810cec2d>] lockdep_rcu_suspicious+0xfd/0x130
 [<ffffffff812d91d1>] sel_netnode_sid+0x3b1/0x3e0
 [<ffffffff812d8e20>] ? sel_netnode_find+0x1a0/0x1a0
 [<ffffffff812d24a6>] selinux_socket_bind+0xf6/0x2c0
 [<ffffffff810cd1dd>] ? trace_hardirqs_off+0xd/0x10
 [<ffffffff810cdb55>] ? lock_release_holdtime.part.9+0x15/0x1a0
 [<ffffffff81093841>] ? lock_hrtimer_base+0x31/0x60
 [<ffffffff812c9536>] security_socket_bind+0x16/0x20
 [<ffffffff815550ca>] sys_bind+0x7a/0x100
 [<ffffffff816c03d5>] ? sysret_check+0x22/0x5d
 [<ffffffff810d392d>] ? trace_hardirqs_on_caller+0x10d/0x1a0
 [<ffffffff8133b09e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
 [<ffffffff816c03a9>] system_call_fastpath+0x16/0x1b

This patch below does what Paul McKenney suggested in the previous thread.

Signed-off-by: Dave Jones <davej@redhat.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Cc: Eric Paris <eparis@parisplace.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
---
 security/selinux/netnode.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/security/selinux/netnode.c b/security/selinux/netnode.c
index 28f911c..c5454c0 100644
--- a/security/selinux/netnode.c
+++ b/security/selinux/netnode.c
@@ -174,7 +174,8 @@  static void sel_netnode_insert(struct sel_netnode *node)
 	if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
 		struct sel_netnode *tail;
 		tail = list_entry(
-			rcu_dereference(sel_netnode_hash[idx].list.prev),
+			rcu_dereference_protected(sel_netnode_hash[idx].list.prev,
+						  lockdep_is_held(&sel_netnode_lock)),
 			struct sel_netnode, list);
 		list_del_rcu(&tail->list);
 		kfree_rcu(tail, rcu);