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.reshet...@intel.com>
Signed-off-by: Hans Liljestrand <ishkam...@gmail.com>
Signed-off-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: David Windsor <dwind...@gmail.com>
---
fs/btrfs/extent_io.c | 4 ++--
fs/btrfs/extent_map.c | 10 +++++-----
fs/btrfs/extent_map.h | 3 ++-
fs/btrfs/tree-log.c | 2 +-
fs/btrfs/volumes.c | 2 +-
include/trace/events/btrfs.h | 2 +-
6 files changed, 12 insertions(+), 11 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index c3abf84..3cf0b02 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2852,7 +2852,7 @@ __get_extent_map(struct inode *inode, struct page *page,
size_t pg_offset,
em = *em_cached;
if (extent_map_in_tree(em) && start >= em->start &&
start < extent_map_end(em)) {
- atomic_inc(&em->refs);
+ refcount_inc(&em->refs);
return em;
}
@@ -2863,7 +2863,7 @@ __get_extent_map(struct inode *inode, struct page *page,
size_t pg_offset,
em = get_extent(BTRFS_I(inode), page, pg_offset, start, len, 0);
if (em_cached && !IS_ERR_OR_NULL(em)) {
BUG_ON(*em_cached);
- atomic_inc(&em->refs);
+ refcount_inc(&em->refs);
*em_cached = em;
}
return em;
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 26f9ac7..6985015 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -55,7 +55,7 @@ struct extent_map *alloc_extent_map(void)
em->flags = 0;
em->compress_type = BTRFS_COMPRESS_NONE;
em->generation = 0;
- atomic_set(&em->refs, 1);
+ refcount_set(&em->refs, 1);
INIT_LIST_HEAD(&em->list);
return em;
}
@@ -71,8 +71,8 @@ void free_extent_map(struct extent_map *em)
{
if (!em)
return;
- WARN_ON(atomic_read(&em->refs) == 0);
- if (atomic_dec_and_test(&em->refs)) {
+ WARN_ON(refcount_read(&em->refs) == 0);
+ if (refcount_dec_and_test(&em->refs)) {
WARN_ON(extent_map_in_tree(em));
WARN_ON(!list_empty(&em->list));
if (test_bit(EXTENT_FLAG_FS_MAPPING, &em->flags))
@@ -322,7 +322,7 @@ static inline void setup_extent_mapping(struct
extent_map_tree *tree,
struct extent_map *em,
int modified)
{
- atomic_inc(&em->refs);
+ refcount_inc(&em->refs);
em->mod_start = em->start;
em->mod_len = em->len;
@@ -381,7 +381,7 @@ __lookup_extent_mapping(struct extent_map_tree *tree,
if (strict && !(end > em->start && start < extent_map_end(em)))
return NULL;
- atomic_inc(&em->refs);
+ refcount_inc(&em->refs);
return em;
}
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index eb8b8fa..a67b2de 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;
};
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index a59674c..ccfe9fe 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -4196,7 +4196,7 @@ static int btrfs_log_changed_extents(struct
btrfs_trans_handle *trans,
if (em->generation <= test_gen)
continue;
/* Need a ref to keep it from getting evicted from cache */
- atomic_inc(&em->refs);
+ refcount_inc(&em->refs);
set_bit(EXTENT_FLAG_LOGGING, &em->flags);
list_add_tail(&em->list, &extents);
num++;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index a8fd2e9..c23a383 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4833,7 +4833,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle
*trans,
ret = add_extent_mapping(em_tree, em, 0);
if (!ret) {
list_add_tail(&em->list, &trans->transaction->pending_chunks);
- atomic_inc(&em->refs);
+ refcount_inc(&em->refs);
}
write_unlock(&em_tree->lock);
if (ret) {
diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h
index a3c3cab..9dd29e8 100644
--- a/include/trace/events/btrfs.h
+++ b/include/trace/events/btrfs.h
@@ -213,7 +213,7 @@ TRACE_EVENT_CONDITION(btrfs_get_extent,
__entry->block_start = map->block_start;
__entry->block_len = map->block_len;
__entry->flags = map->flags;
- __entry->refs = atomic_read(&map->refs);
+ __entry->refs = refcount_read(&map->refs);
__entry->compress_type = map->compress_type;
),
--
2.7.4
