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From: Dave Jones <>
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Subject: Fix sel_netnode_insert suspicious rcu dereference.
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I reported this a year ago (https://lkml.org/lkml/2011/4/20/308).
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It's still a problem apparently ...
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===============================
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[ INFO: suspicious RCU usage. ]
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3.5.0-rc1+ #63 Not tainted
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-------------------------------
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security/selinux/netnode.c:178 suspicious rcu_dereference_check() usage!
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other info that might help us debug this:
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rcu_scheduler_active = 1, debug_locks = 0
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1 lock held by trinity-child1/8750:
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#0: (sel_netnode_lock){+.....}, at: [<ffffffff812d8f8a>] sel_netnode_sid+0x16a/0x3e0
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stack backtrace:
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Pid: 8750, comm: trinity-child1 Not tainted 3.5.0-rc1+ #63
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Call Trace:
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[<ffffffff810cec2d>] lockdep_rcu_suspicious+0xfd/0x130
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[<ffffffff812d91d1>] sel_netnode_sid+0x3b1/0x3e0
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[<ffffffff812d8e20>] ? sel_netnode_find+0x1a0/0x1a0
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[<ffffffff812d24a6>] selinux_socket_bind+0xf6/0x2c0
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[<ffffffff810cd1dd>] ? trace_hardirqs_off+0xd/0x10
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[<ffffffff810cdb55>] ? lock_release_holdtime.part.9+0x15/0x1a0
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[<ffffffff81093841>] ? lock_hrtimer_base+0x31/0x60
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[<ffffffff812c9536>] security_socket_bind+0x16/0x20
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[<ffffffff815550ca>] sys_bind+0x7a/0x100
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[<ffffffff816c03d5>] ? sysret_check+0x22/0x5d
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[<ffffffff810d392d>] ? trace_hardirqs_on_caller+0x10d/0x1a0
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[<ffffffff8133b09e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
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[<ffffffff816c03a9>] system_call_fastpath+0x16/0x1b
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This patch below does what Paul McKenney suggested in the previous thread.
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Signed-off-by: Dave Jones <davej@redhat.com>
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diff --git a/security/selinux/netnode.c b/security/selinux/netnode.c
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index 28f911c..c5454c0 100644
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--- a/security/selinux/netnode.c
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+++ b/security/selinux/netnode.c
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@@ -174,7 +174,8 @@ static void sel_netnode_insert(struct sel_netnode *node)
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if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
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struct sel_netnode *tail;
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tail = list_entry(
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- rcu_dereference(sel_netnode_hash[idx].list.prev),
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+ rcu_dereference_protected(sel_netnode_hash[idx].list.prev,
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+ lockdep_is_held(&sel_netnode_lock)),
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struct sel_netnode, list);
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list_del_rcu(&tail->list);
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kfree_rcu(tail, rcu);
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