audit: Fix use after free in audit_remove_watch_rule()

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audit_remove_watch_rule() drops watch's reference to parent but then
continues to work with it. That is not safe as parent can get freed once
we drop our reference. The following is a trivial reproducer:

mount -o loop image /mnt
touch /mnt/file
auditctl -w /mnt/file -p wax
umount /mnt
auditctl -D
<crash in fsnotify_destroy_mark()>

Grab our own reference in audit_remove_watch_rule() earlier to make sure
mark does not get freed under us.

CC: stable@vger.kernel.org
Reported-by: Tony Jones <tonyj@suse.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Tested-by: Tony Jones <tonyj@suse.de>
Signed-off-by: Paul Moore <paul@paul-moore.com>

...

This commit is contained in:

Jan Kara 2017-08-15 13:00:36 +02:00 • committed by Paul Moore

parent b0659ae5e3

commit d76036ab47

1 changed files with 7 additions and 5 deletions

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kernel/audit_watch.c

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