[PATCH 2/2] fs: btrfs: Don't leak memory when failing add fsid

Tobin C. Harding
2019-05-13T03:40:28Z

A failed call to kobject_init_and_add() must be followed by a call to
kobject_put(). Currently in the error path when adding fs_devices we
are missing this call. This could be fixed by calling
btrfs_sysfs_remove_fsid() if btrfs_sysfs_add_fsid() returns an error or
by adding a call to kobject_put() directly in btrfs_sysfs_add_fsid().
Here we choose the second option because it prevents the slightly
unusual error path handling requirements of kobject from leaking out
into btrfs functions.

Add a call to kobject_put() in the error path of kobject_add_and_init().
This causes the release method to be called if kobject_init_and_add()
fails. open_tree() is the function that calls btrfs_sysfs_add_fsid()
and the error code in this function is already written with the
assumption that the release method is called during the error path of
open_tree() (as seen by the call to btrfs_sysfs_remove_fsid() under the
fail_fsdev_sysfs label).

Signed-off-by: Tobin C. Harding <tobin@kernel.org>
---
fs/btrfs/sysfs.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 5a5930e3d32b..2f078b77fe14 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -825,7 +825,12 @@ int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
fs_devs->fsid_kobj.kset = btrfs_kset;
error = kobject_init_and_add(&fs_devs->fsid_kobj,
&btrfs_ktype, parent, "%pU", fs_devs->fsid);
- return error;
+ if (error) {
+ kobject_put(&fs_devs->fsid_kobj);
+ return error;
+ }
+
+ return 0;
}

int btrfs_sysfs_add_mounted(struct btrfs_fs_info *fs_info)
--
2.21.0