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Fix sel_netnode_insert suspicious rcu dereference.

PATCH Dave Jones 4 participants 5 messages Jun 5, 2012 – Aug 6, 2012 SELinux security module

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Dave Jones

author
#0 lore raw

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 <[email protected]>
security/selinux/netnode.c +2 -1
index 28f911c..c5454c0 100644
@@ -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);
author
#1 lore raw
Quoted 2 lines · Dave Jones

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

Quoted 49 lines

===============================
[ 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 <[email protected]>
security/selinux/netnode.c +2 -2
index 28f911c..c5454c0 100644
@@ -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);
--
Quoted 4 lines

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---end quoted text---

maintainer Acked-by
#2 lore raw
Quoted 10 lines · Dave Jones
Quoted 2 lines · Dave Jones

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 <[email protected]>
Signature · 2 lines
paul moore
www.paul-moore.com
#3 lore raw

I thought I HAD committed it months ago!

Man I suck at this....

Quoted 27 lines · Paul Moore
Quoted 10 lines · Dave Jones
Quoted 2 lines · Dave Jones

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 <[email protected]>

--
paul moore
www.paul-moore.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected]
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Please read the FAQ at http://www.tux.org/lkml/

Reviewed-by
#4 lore raw
In reply to Dave Jones
Quoted 10 lines · Dave Jones
Quoted 2 lines · Dave Jones

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 <[email protected]>

in case that helps.

Thanx, Paul

Quoted 58 lines

Dave

Quoted 49 lines

===============================
[ 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 <[email protected]>
security/selinux/netnode.c +2 -2
index 28f911c..c5454c0 100644
@@ -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);
--
Quoted 4 lines

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Please read the FAQ at http://www.tux.org/lkml/

---end quoted text---