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@xxxxxxxxx>
Signed-off-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: David Windsor <dwindsor@xxxxxxxxx>
---
fs/btrfs/ctree.h | 2 +-
fs/btrfs/disk-io.c | 2 +-
fs/btrfs/disk-io.h | 4 ++--
3 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 557af39..c01bfca 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1221,7 +1221,7 @@ struct btrfs_root {
dev_t anon_dev;
spinlock_t root_item_lock;
- atomic_t refs;
+ refcount_t refs;
struct mutex delalloc_mutex;
spinlock_t delalloc_lock;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 913df60..ca89ae3 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1340,7 +1340,7 @@ static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info,
atomic_set(&root->log_writers, 0);
atomic_set(&root->log_batch, 0);
atomic_set(&root->orphan_inodes, 0);
- atomic_set(&root->refs, 1);
+ refcount_set(&root->refs, 1);
atomic_set(&root->will_be_snapshoted, 0);
atomic_set(&root->qgroup_meta_rsv, 0);
root->log_transid = 0;
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index 2e0ec29..21f1ceb 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -101,14 +101,14 @@ struct btrfs_root *btrfs_alloc_dummy_root(struct btrfs_fs_info *fs_info);
*/
static inline struct btrfs_root *btrfs_grab_fs_root(struct btrfs_root *root)
{
- if (atomic_inc_not_zero(&root->refs))
+ if (refcount_inc_not_zero(&root->refs))
return root;
return NULL;
}
static inline void btrfs_put_fs_root(struct btrfs_root *root)
{
- if (atomic_dec_and_test(&root->refs))
+ if (refcount_dec_and_test(&root->refs))
kfree(root);
}
--
2.7.4
