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Commit a2140fc0 authored by Miklos Szeredi's avatar Miklos Szeredi
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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: default avatarMiklos Szeredi <mszeredi@suse.cz>
Reported-by: default avatarValentin Avram <aval13@gmail.com>
Reported-by: default avatarPeter Moody <pmoody@google.com>
Acked-by: default avatarEric Paris <eparis@redhat.com>
CC: stable@vger.kernel.org
parent 0fe33aae
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