Fix sel_netnode_insert suspicious rcu dereference.

Fix sel_netnode_insert suspicious rcu dereference.

[Dave Jones]

I reported this a year ago (https://lkml.org/lkml/2011/4/20/308).
It's still a problem apparently ...

===============================
[ 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>

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);

Re: Fix sel_netnode_insert suspicious rcu dereference.

[Dave Jones]

On Tue, Jun 05, 2012 at 01:12:39AM -0400, Dave Jones wrote:
 > I reported this a year ago (https://lkml.org/lkml/2011/4/20/308).
 > It's still a problem apparently ...

And another two months pass in silence.

This is happening to other people too.
https://bugzilla.redhat.com/show_bug.cgi?id=846037

Can someone please apply this patch, or at least point out what's wrong with it ?

	Dave

 
 > ===============================
 > [ 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>
 > 
 > 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);
 > --
 > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
 > the body of a message to majordomo@vger.kernel.org
 > More majordomo info at  http://vger.kernel.org/majordomo-info.html
 > Please read the FAQ at  http://www.tux.org/lkml/
---end quoted text---

Re: Fix sel_netnode_insert suspicious rcu dereference.

[Paul E. McKenney]

On Mon, Aug 06, 2012 at 12:49:14PM -0400, Dave Jones wrote:
> On Tue, Jun 05, 2012 at 01:12:39AM -0400, Dave Jones wrote:
>  > I reported this a year ago (https://lkml.org/lkml/2011/4/20/308).
>  > It's still a problem apparently ...
> 
> And another two months pass in silence.
> 
> This is happening to other people too.
> https://bugzilla.redhat.com/show_bug.cgi?id=846037
> 
> Can someone please apply this patch, or at least point out what's wrong with it ?

Feel free to add:

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

in case that helps.

							Thanx, Paul

> 	Dave
> 
> 
>  > ===============================
>  > [ 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>
>  > 
>  > 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);
>  > --
>  > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>  > the body of a message to majordomo@vger.kernel.org
>  > More majordomo info at  http://vger.kernel.org/majordomo-info.html
>  > Please read the FAQ at  http://www.tux.org/lkml/
> ---end quoted text---
> 

Re: Fix sel_netnode_insert suspicious rcu dereference.

[Paul Moore]

On Mon, Aug 6, 2012 at 12:49 PM, Dave Jones <davej@redhat.com> wrote:
> On Tue, Jun 05, 2012 at 01:12:39AM -0400, Dave Jones wrote:
>  > I reported this a year ago (https://lkml.org/lkml/2011/4/20/308).
>  > It's still a problem apparently ...
>
> And another two months pass in silence.
>
> This is happening to other people too.
> https://bugzilla.redhat.com/show_bug.cgi?id=846037
>
> Can someone please apply this patch, or at least point out what's wrong with it ?

I thought Eric had applied it a few months ago, but I just checked and
I don't see it in Linus' tree for some reason?  I know multiple
patches have been posted from different authors, all fixing the same
thing ...

Acked-by: Paul Moore <paul@paul-moore.com>

-- 
paul moore
www.paul-moore.com

Re: Fix sel_netnode_insert suspicious rcu dereference.

[Eric Paris]

I thought I HAD committed it months ago!

Man I suck at this....

On Mon, Aug 6, 2012 at 3:10 PM, Paul Moore <paul@paul-moore.com> wrote:
> On Mon, Aug 6, 2012 at 12:49 PM, Dave Jones <davej@redhat.com> wrote:
>> On Tue, Jun 05, 2012 at 01:12:39AM -0400, Dave Jones wrote:
>>  > I reported this a year ago (https://lkml.org/lkml/2011/4/20/308).
>>  > It's still a problem apparently ...
>>
>> And another two months pass in silence.
>>
>> This is happening to other people too.
>> https://bugzilla.redhat.com/show_bug.cgi?id=846037
>>
>> Can someone please apply this patch, or at least point out what's wrong with it ?
>
> I thought Eric had applied it a few months ago, but I just checked and
> I don't see it in Linus' tree for some reason?  I know multiple
> patches have been posted from different authors, all fixing the same
> thing ...
>
> Acked-by: Paul Moore <paul@paul-moore.com>
>
> --
> paul moore
> www.paul-moore.com
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/