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* [PATCH] kmemleak: Protect the seq start/next/stop sequence by rcu_read_lock()
@ 2009-07-29 15:26 Catalin Marinas
  2009-07-30  0:00 ` Andrew Morton
  2009-08-02 11:14 ` Ingo Molnar
  0 siblings, 2 replies; 26+ messages in thread
From: Catalin Marinas @ 2009-07-29 15:26 UTC (permalink / raw)
  To: Linus Torvalds; +Cc: Andrew Morton, linux-kernel

Objects passed to kmemleak_seq_next() have an incremented reference
count (hence not freed) but they may point via object_list.next to
other freed objects. To avoid this, the whole start/next/stop sequence
must be protected by rcu_read_lock().

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---

This is a fix for bug #13761 in buzilla.kernel.org. If there are no
objections, please apply it before 2.6.31. Thanks.

 mm/kmemleak.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 5aabd41..4872673 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1217,7 +1217,6 @@ static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
 	}
 	object = NULL;
 out:
-	rcu_read_unlock();
 	return object;
 }
 
@@ -1233,13 +1232,11 @@ static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 
 	++(*pos);
 
-	rcu_read_lock();
 	list_for_each_continue_rcu(n, &object_list) {
 		next_obj = list_entry(n, struct kmemleak_object, object_list);
 		if (get_object(next_obj))
 			break;
 	}
-	rcu_read_unlock();
 
 	put_object(prev_obj);
 	return next_obj;
@@ -1255,6 +1252,7 @@ static void kmemleak_seq_stop(struct seq_file *seq, void *v)
 		 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
 		 * waiting was interrupted, so only release it if !IS_ERR.
 		 */
+		rcu_read_unlock();
 		mutex_unlock(&scan_mutex);
 		if (v)
 			put_object(v);


^ permalink raw reply related	[flat|nested] 26+ messages in thread
end of thread, other threads:[~2009-08-16 21:49 UTC | newest]

Thread overview: 26+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2009-07-29 15:26 [PATCH] kmemleak: Protect the seq start/next/stop sequence by rcu_read_lock() Catalin Marinas
2009-07-30  0:00 ` Andrew Morton
2009-07-30  8:24   ` Catalin Marinas
2009-08-02 11:14 ` Ingo Molnar
2009-08-10 15:55   ` Catalin Marinas
2009-08-10 18:45     ` Ingo Molnar
2009-08-10 22:56       ` Catalin Marinas
2009-08-11  7:32         ` Ingo Molnar
2009-08-11  8:55           ` Catalin Marinas
2009-08-12 12:17             ` Catalin Marinas
2009-08-12 15:32               ` Linus Torvalds
2009-08-12 15:39                 ` Catalin Marinas
2009-08-12 20:52               ` Ingo Molnar
2009-08-12 22:16                 ` kmemleak: Protect the seq start/next/stop sequence byrcu_read_lock() Catalin Marinas
2009-08-13  6:52                   ` Ingo Molnar
2009-08-13  9:39                     ` Catalin Marinas
2009-08-13  9:44                       ` Ingo Molnar
2009-08-13 14:44                         ` Catalin Marinas
2009-08-14 22:45                 ` Catalin Marinas
2009-08-14 22:47                   ` [PATCH] kmemleak: Allow rescheduling during an object scanning Catalin Marinas
2009-08-14 22:48                   ` [PATCH] kmemleak: Ignore the aperture memory hole on x86_64 Catalin Marinas
2009-08-15 14:17                     ` Ingo Molnar
2009-08-15 22:34                       ` Catalin Marinas
2009-08-16  7:04                         ` Ingo Molnar
2009-08-16 10:08                     ` Ingo Molnar
2009-08-16 21:48                       ` Catalin Marinas

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