debugfs: allow bad parent pointers to be passed in

If something went wrong with creating a debugfs file/symlink/directory, that value could be passed down into debugfs again as a parent dentry. To make caller code simpler, just error out if this happens, and don't crash the kernel.

Reported-by Alex Elder <[email protected]>

Cc Viresh Kumar <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 fs/debugfs/inode.c |    3 +++
 1 file changed, 3 insertions(+)

If something went wrong with creating a debugfs file/symlink/directory, that value could be passed down into debugfs again as a parent dentry. To make caller code simpler, just error out if this happens, and don't crash the kernel.

Reported-by Alex Elder <[email protected]>

Cc Viresh Kumar <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 fs/debugfs/inode.c |    3 +++
 1 file changed, 3 insertions(+)

fs/debugfs/inode.c +3 -0

@@ -254,6 +254,9 @@ static struct dentry *start_creating(con
 
 	pr_debug("debugfs: creating file '%s'\n",name);
 
+	if (IS_ERR(parent))
+		return parent;
+
 	error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
 			      &debugfs_mount_count);
 	if (error)