[PATCH] audit: make sure we don't let the retry queue grow without bounds

[Seth Forshee]

On Mon, Apr 10, 2017 at 04:54:27PM -0400, Paul Moore wrote:
> From: Paul Moore <paul at paul-moore.com>
> 
> The retry queue is intended to provide a temporary buffer in the case
> of transient errors when communicating with auditd, it is not meant
> as a long life queue, that functionality is provided by the hold
> queue.
> 
> This patch fixes a problem identified by Seth where the retry queue
> could grow uncontrollably if an auditd instance did not connect to
> the kernel to drain the queues.  This commit fixes this by doing the
> following:
> 
> * Make sure we always call auditd_reset() if we decide the connection
> with audit is really dead.  There were some cases in
> kauditd_hold_skb() where we did not reset the connection, this patch
> relocates the reset calls to kauditd_thread() so all the error
> conditions are caught and the connection reset.  As a side effect,
> this means we could move auditd_reset() and get rid of the forward
> definition at the top of kernel/audit.c.
> 
> * We never checked the status of the auditd connection when
> processing the main audit queue which meant that the retry queue
> could grow unchecked.  This patch adds a call to auditd_reset()
> after the main queue has been processed if auditd is not connected,
> the auditd_reset() call will make sure the retry and hold queues are
> correctly managed/flushed so that the retry queue remains reasonable.
> 
> Reported-by: Seth Forshee <seth.forshee at canonical.com>
> Signed-off-by: Paul Moore <paul at paul-moore.com>

That fixes the issues I reported. The fix is also needed in 4.10 stable.

Thanks,
Seth