audit: fix refcounting in audit-tree
audit: fix refcounting in audit-tree

Refcounting of fsnotify_mark in audit tree is broken.  E.g:

                              refcount
create_chunk
  alloc_chunk                 1
  fsnotify_add_mark           2

untag_chunk
  fsnotify_get_mark           3
  fsnotify_destroy_mark
    audit_tree_freeing_mark   2
  fsnotify_put_mark           1
  fsnotify_put_mark           0
  via destroy_list
    fsnotify_mark_destroy    -1

This was reported by various people as triggering Oops when stopping auditd.

We could just remove the put_mark from audit_tree_freeing_mark() but that would
break freeing via inode destruction.  So this patch simply omits a put_mark
after calling destroy_mark or adds a get_mark before.

The additional get_mark is necessary where there's no other put_mark after
fsnotify_destroy_mark() since it assumes that the caller is holding a reference
(or the inode is keeping the mark pinned, not the case here AFAICS).

Signed-off-by: Miklos Szeredi <84cd5483a2f9acd1c37251cba7c2908448f221b8@suse.cz>
Reported-by: Valentin Avram <c0f85732e27a08f0fccef3a0ad97c3e166afbc3f@gmail.com>
Reported-by: Peter Moody <c73b7d41580ef9050e926427523c2d206506aa60@google.com>
Acked-by: Eric Paris <b0b36e3cd9ea4e5739ff430a3056fabf2fdb0376@redhat.com>
CC: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs