Re: [RFC PATCH v3] audit: use proper refcount locking on audit_sock
On Tue, Dec 13, 2016 at 8:00 PM, Richard Guy Briggs <rgb(a)redhat.com> wrote:
On 2016-12-13 16:19, Cong Wang wrote:
> On Tue, Dec 13, 2016 at 7:03 AM, Richard Guy Briggs <rgb(a)redhat.com> wrote:
> > @@ -1283,8 +1299,10 @@ static void __net_exit audit_net_exit(struct net *net)
> > {
> > struct audit_net *aunet = net_generic(net, audit_net_id);
> > struct sock *sock = aunet->nlsk;
> > + mutex_lock(&audit_cmd_mutex);
> > if (sock == audit_sock)
> > auditd_reset();
> > + mutex_unlock(&audit_cmd_mutex);
>
> This still doesn't look correct to me, b/c here we release the audit_sock
> refcnt twice:
>
> 1) inside audit_reset()
The audit_reset() refcount decrement corresponds to a setting of
audit_sock only if audit_sock is still non-NULL.
Hmm, thinking about it again, looks like the sock == audit_sock
and audit_sock != NULL checks can guarantee we are safe. So,
Reviewed-by: Cong Wang <xiyou.wangcong(a)gmail.com>