linux-kernel - [PATCH 1/3] kmemleak: Release the object lock before calling put

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Message-ID: <20091028171820.19220.70957.stgit@pc1117.cambridge.arm.com>
Date:	Wed, 28 Oct 2009 17:18:20 +0000
From:	Catalin Marinas <catalin.marinas@....com>
To:	linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] kmemleak: Release the object lock before calling
	put_object()

The put_object() function may free the object if the use_count
dropped to 0. There shouldn't be further accesses to such object unless
it is known that the use_count is non-zero.

Signed-off-by: Catalin Marinas <catalin.marinas@....com>
---
 mm/kmemleak.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 9610635..f06c092 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1025,11 +1025,14 @@ static void scan_block(void *_start, void *_end,
 		 * added to the gray_list.
 		 */
 		object->count++;
-		if (color_gray(object))
+		if (color_gray(object)) {
 			list_add_tail(&object->gray_list, &gray_list);
-		else
-			put_object(object);
+			spin_unlock_irqrestore(&object->lock, flags);
+			continue;
+		}
+
 		spin_unlock_irqrestore(&object->lock, flags);
+		put_object(object);
 	}
 }
 

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