From: Tejun Heo <tj@kernel.org>
To: "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>
Cc: Vivek Goyal <vgoyal@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Fix use-after-free of q->root_blkg and q->root_rl.blkg
Date: Tue, 16 Oct 2012 16:20:40 -0700 [thread overview]
Message-ID: <20121016232040.GH16166@google.com> (raw)
In-Reply-To: <50762182.5090806@ce.jp.nec.com>
Hello,
On Thu, Oct 11, 2012 at 10:31:46AM +0900, Jun'ichi Nomura wrote:
> >> - if (ent == &q->root_blkg->q_node)
> >> + if (q->root_blkg && ent == &q->root_blkg->q_node)
> >
> > Can we fix it little differently. Little earlier in the code, we check for
> > if q->blkg_list is empty, then all the groups are gone, and there are
> > no more request lists hence and return NULL.
> >
> > Current code:
> > if (rl == &q->root_rl) {
> > ent = &q->blkg_list;
> >
> > Modified code:
> > if (rl == &q->root_rl) {
> > ent = &q->blkg_list;
> > /* There are no more block groups, hence no request lists */
> > if (list_empty(ent))
> > return NULL;
> > }
Do we need this at all? q->root_blkg being NULL is completely fine
there and the comparison would work as expected, no?
Thanks.
--
tejun
next prev parent reply other threads:[~2012-10-16 23:20 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-10 5:11 [PATCH] Fix use-after-free of q->root_blkg and q->root_rl.blkg Jun'ichi Nomura
2012-10-10 15:59 ` Vivek Goyal
2012-10-11 1:31 ` Jun'ichi Nomura
2012-10-11 18:55 ` Vivek Goyal
2012-10-16 23:20 ` Tejun Heo [this message]
2012-10-17 0:02 ` Jun'ichi Nomura
2012-10-17 8:45 ` [PATCH] blkcg: " Jun'ichi Nomura
2012-10-18 21:21 ` Tejun Heo
2012-10-22 18:43 ` Jens Axboe
2012-10-17 13:47 ` [PATCH] " Vivek Goyal
2012-10-18 2:56 ` Jun'ichi Nomura
2012-10-18 13:31 ` Vivek Goyal
2012-10-18 21:20 ` Tejun Heo
2012-10-19 14:53 ` Vivek Goyal
2012-10-22 0:55 ` Jun'ichi Nomura
2012-10-22 1:15 ` [PATCH] blkcg: stop iteration early if root_rl is the only request list Jun'ichi Nomura
2012-10-22 15:31 ` Vivek Goyal
2012-10-22 18:43 ` Jens Axboe
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