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SubjectRe: Fix sel_netnode_insert suspicious rcu dereference.
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
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> ---end quoted text---
>



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