From: Manfred Spraul <manfred@colorfullife.com>
To: Davidlohr Bueso <davidlohr@hp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>, Mike Galbraith <efault@gmx.de>,
sedat.dilek@gmail.com,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/4] ipc,shm: prevent race with rmid in shmat(2)
Date: Fri, 27 Sep 2013 07:45:01 +0200 [thread overview]
Message-ID: <52451B5D.4080908@colorfullife.com> (raw)
In-Reply-To: <1379300677-24188-3-git-send-email-davidlohr@hp.com>
Hi Davidlohr,
On 09/16/2013 05:04 AM, Davidlohr Bueso wrote:
> This fixes a race in shmat() between finding the msq and
> actually attaching the segment, as another thread can delete shmid
> underneath us if we are preempted before acquiring the kern_ipc_perm.lock.
According the the man page, Linux supports attaching to deleted shm
segments:
http://linux.die.net/man/2/shmat
>
> On Linux, it is possible to attach a shared memory segment even if it
> is already marked to be deleted. However, POSIX.1-2001 does not
> specify this behavior and many other implementations do not support it.
>
Does your patch change that?
Unfortunately, I have neither any experience with ipc/shm nor any test
cases.
And:
As far as I can see it's not a problem if we are attaching to a deleted
segment: shm_close cleans up everything.
--
Manfred
next prev parent reply other threads:[~2013-09-27 5:45 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-16 3:04 [PATCH 0/4] ipc: shm and msg fixes Davidlohr Bueso
2013-09-16 3:04 ` [PATCH 1/4] ipc,shm: fix race with selinux Davidlohr Bueso
2013-09-16 9:23 ` Manfred Spraul
2013-09-16 3:04 ` [PATCH 2/4] ipc,shm: prevent race with rmid in shmat(2) Davidlohr Bueso
2013-09-27 5:45 ` Manfred Spraul [this message]
2013-09-27 23:40 ` Davidlohr Bueso
2013-09-16 3:04 ` [PATCH 3/4] ipc,msg: fix race with selinux Davidlohr Bueso
2013-09-16 3:04 ` [PATCH 4/4] ipc,msg: prevent race with rmid in msgsnd,msgrcv Davidlohr Bueso
2013-09-27 5:50 ` Manfred Spraul
2013-09-19 21:22 ` [PATCH 0/4] ipc: shm and msg fixes Davidlohr Bueso
2013-09-20 18:08 ` Eric Paris
2013-09-21 18:30 ` Davidlohr Bueso
2013-09-21 18:58 ` Linus Torvalds
2013-09-23 6:42 ` Davidlohr Bueso
2013-09-23 16:54 ` Linus Torvalds
2013-09-24 0:04 ` Davidlohr Bueso
2013-09-24 1:22 ` Linus Torvalds
2013-09-24 8:49 ` Manfred Spraul
2013-09-24 9:05 ` Manfred Spraul
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