From 490b54d6fb75f6ffd0471ec58bb38a992e2b40cd Mon Sep 17 00:00:00 2001
From: Elena Reshetova <elena.reshetova@intel.com>
Date: Fri, 3 Mar 2017 10:55:12 +0200
Subject: btrfs: convert extent_map.refs from atomic_t to refcount_t

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/extent_map.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'fs/btrfs/extent_map.h')

diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index eb8b8fae036b..a67b2def5413 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -2,6 +2,7 @@
 #define __EXTENTMAP__
 
 #include <linux/rbtree.h>
+#include <linux/refcount.h>
 
 #define EXTENT_MAP_LAST_BYTE ((u64)-4)
 #define EXTENT_MAP_HOLE ((u64)-3)
@@ -41,7 +42,7 @@ struct extent_map {
 		 */
 		struct map_lookup *map_lookup;
 	};
-	atomic_t refs;
+	refcount_t refs;
 	unsigned int compress_type;
 	struct list_head list;
 };
-- 
cgit v1.2.3