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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=52451B5D.4080908@colorfullife.com \
--to=manfred@colorfullife.com \
--cc=akpm@linux-foundation.org \
--cc=davidlohr@hp.com \
--cc=efault@gmx.de \
--cc=linux-kernel@vger.kernel.org \
--cc=riel@redhat.com \
--cc=sedat.dilek@gmail.com \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.