auditsc: audit_krule mask accesses need bounds checking

auditsc: audit_krule mask accesses need bounds checking

Fixes an easy DoS and possible information disclosure.

This does nothing about the broken state of x32 auditing.

eparis: If the admin has enabled auditd and has specifically loaded
audit rules.  This bug has been around since before git.  Wow...

Cc: stable@vger.kernel.org
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit a3c54931199565930d6d84f4c3456f6440aefd41)
[wt: no audit_filter_inode_name(), applied to audit_filter_inodes() instead]
Signed-off-by: Willy Tarreau <w@1wt.eu>