queue-4.4/btrfs-sysfs-don-t-leak-memory-when-failing-add-fsid.patch

   1 From e32773357d5cc271b1d23550b3ed026eb5c2a468 Mon Sep 17 00:00:00 2001
   2 From: "Tobin C. Harding" <tobin@kernel.org>
   3 Date: Mon, 13 May 2019 13:39:12 +1000
   4 Subject: btrfs: sysfs: don't leak memory when failing add fsid
   5
   6 From: Tobin C. Harding <tobin@kernel.org>
   7
   8 commit e32773357d5cc271b1d23550b3ed026eb5c2a468 upstream.
   9
  10 A failed call to kobject_init_and_add() must be followed by a call to
  11 kobject_put().  Currently in the error path when adding fs_devices we
  12 are missing this call.  This could be fixed by calling
  13 btrfs_sysfs_remove_fsid() if btrfs_sysfs_add_fsid() returns an error or
  14 by adding a call to kobject_put() directly in btrfs_sysfs_add_fsid().
  15 Here we choose the second option because it prevents the slightly
  16 unusual error path handling requirements of kobject from leaking out
  17 into btrfs functions.
  18
  19 Add a call to kobject_put() in the error path of kobject_add_and_init().
  20 This causes the release method to be called if kobject_init_and_add()
  21 fails.  open_tree() is the function that calls btrfs_sysfs_add_fsid()
  22 and the error code in this function is already written with the
  23 assumption that the release method is called during the error path of
  24 open_tree() (as seen by the call to btrfs_sysfs_remove_fsid() under the
  25 fail_fsdev_sysfs label).
  26
  27 Cc: stable@vger.kernel.org # v4.4+
  28 Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  29 Signed-off-by: Tobin C. Harding <tobin@kernel.org>
  30 Reviewed-by: David Sterba <dsterba@suse.com>
  31 Signed-off-by: David Sterba <dsterba@suse.com>
  32 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  33
  34 ---
  35  fs/btrfs/sysfs.c |    7 ++++++-
  36  1 file changed, 6 insertions(+), 1 deletion(-)
  37
  38 --- a/fs/btrfs/sysfs.c
  39 +++ b/fs/btrfs/sysfs.c
  40 @@ -733,7 +733,12 @@ int btrfs_sysfs_add_fsid(struct btrfs_fs
  41         fs_devs->fsid_kobj.kset = btrfs_kset;
  42         error = kobject_init_and_add(&fs_devs->fsid_kobj,
  43                                 &btrfs_ktype, parent, "%pU", fs_devs->fsid);
  44 -       return error;
  45 +       if (error) {
  46 +               kobject_put(&fs_devs->fsid_kobj);
  47 +               return error;
  48 +       }
  49 +
  50 +       return 0;
  51  }
  52
  53  int btrfs_sysfs_add_mounted(struct btrfs_fs_info *fs_info)