getname_kernel() needs to make sure that ->name != ->iname in long case

commit 30ce4d1 upstream.

missed it in "kill struct filename.separate" several years ago.

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/namei.c

@@ -222,9 +222,10 @@ getname_kernel(const char * filename)
  if (len <= EMBEDDED_NAME_MAX) {
  result->name = (char *)result->iname;
  } else if (len <= PATH_MAX) {
+ const size_t size = offsetof(struct filename, iname[1]);
  struct filename *tmp;
 
- tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);
+ tmp = kmalloc(size, GFP_KERNEL);
  if (unlikely(!tmp)) {
  __putname(result);
  return ERR_PTR(-ENOMEM);