From: Vasiliy Kulikov <segoon@openwall.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: akpm@linux-foundation.org,
Serge Hallyn <serge.hallyn@canonical.com>,
daniel.lezcano@free.fr, ebiederm@xmission.com, mingo@elte.hu,
rdunlap@xenotime.net, tj@kernel.org,
kernel-hardening@lists.openwall.com
Subject: [kernel-hardening] Re: [PATCH] shm: handle separate PID namespaces case
Date: Mon, 4 Jul 2011 19:26:36 +0400 [thread overview]
Message-ID: <20110704152636.GA21350@albatros> (raw)
In-Reply-To: <20110704150513.GA6893@redhat.com>
On Mon, Jul 04, 2011 at 17:05 +0200, Oleg Nesterov wrote:
> On 07/04, Vasiliy Kulikov wrote:
> >
> > @@ -239,7 +239,23 @@ static int shm_try_destroy_current(int id, void *p, void *data)
> > if (IS_ERR(shp))
> > return 0;
> >
> > - if (shp->shm_cprid != task_tgid_vnr(current)) {
> > + if (shp->shm_creator != current) {
> > + shm_unlock(shp);
> > + return 0;
>
> I know absolutely nothing about ipc/, so probably I am wrong. But do
> we really need shm_lock()
It is needed to protect against parallel reads. To read one may just
hold shm_lock, but to write both shm_lock and rw_mutex are needed.
> (which also another idr_find)
Yes, this is a waste of time, actually. Directly locking
->shm_perm->lock is what is needed here and in shm_try_destroy_orphaned().
Thanks for looking into this!
--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
next prev parent reply other threads:[~2011-07-04 15:26 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <201106292214.p5TMEtHg015372@imap1.linux-foundation.org>
[not found] ` <20110630134855.GA6165@mail.hallyn.com>
2011-06-30 13:57 ` [kernel-hardening] Re: + ipc-introduce-shm_rmid_forced-sysctl.patch added to -mm tree Vasiliy Kulikov
2011-07-03 18:00 ` Vasiliy Kulikov
2011-07-04 11:55 ` [kernel-hardening] [PATCH] shm: handle separate PID namespaces case Vasiliy Kulikov
2011-07-04 15:05 ` [kernel-hardening] " Oleg Nesterov
2011-07-04 15:26 ` Vasiliy Kulikov [this message]
2011-07-04 15:37 ` Oleg Nesterov
2011-07-04 15:48 ` Vasiliy Kulikov
2011-07-04 17:01 ` [kernel-hardening] [PATCH] shm: optimize locking and ipc_namespace getting Vasiliy Kulikov
2011-07-04 17:29 ` [kernel-hardening] " Oleg Nesterov
2011-07-04 17:51 ` Vasiliy Kulikov
2011-07-05 17:38 ` [kernel-hardening] [PATCH v2] " Vasiliy Kulikov
2011-07-05 17:37 ` [kernel-hardening] [PATCH v2] shm: handle separate PID namespaces case Vasiliy Kulikov
2011-07-15 6:45 ` [kernel-hardening] " Vasiliy Kulikov
2011-07-05 14:26 ` [kernel-hardening] Re: [PATCH] " Serge Hallyn
2011-07-05 14:50 ` Vasiliy Kulikov
2011-07-05 15:57 ` Serge Hallyn
2011-07-05 17:42 ` Vasiliy Kulikov
2011-07-06 16:31 ` Serge Hallyn
2011-07-06 16:57 ` Vasiliy Kulikov
2011-07-06 18:08 ` Oleg Nesterov
2011-07-06 18:35 ` Vasiliy Kulikov
2011-07-05 17:29 ` Vasiliy Kulikov
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