sysfs: make __sysfs_add_one() fail if the parent isn't a directory

Currently the kobject based interface guarantees that a parent
sysfs_dirent is always a directory; however, the planned kernfs
interface will be directly based on sysfs_dirents and the caller may
specify non-directory node as the parent.  Add an explicit check in
__sysfs_add_one() so that such attempts fail with -EINVAL.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index b3cf61dc57c1..98701c00b9b0 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -429,6 +429,9 @@ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
                 return -EINVAL;
         }
 
+        if (sysfs_type(parent_sd) != SYSFS_DIR)
+                return -EINVAL;
+
         sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
         sd->s_parent = sysfs_get(parent_sd);