linux-kernel - Re: [PATCH 2/2] mm/linux-next: Fix rcu locking in vm_is

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAAHN_R1dLONPzzD7bMGV5wMiKzeY3K=u_q6qinpKG-N7gKdssg@mail.gmail.com>
Date:	Wed, 7 Mar 2012 21:35:29 +0530
From:	Siddhesh Poyarekar <siddhesh.poyarekar@...il.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Mark Salter <msalter@...hat.com>,
	linux-next <linux-next@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: Re: [PATCH 2/2] mm/linux-next: Fix rcu locking in vm_is_stack

On Wed, Mar 7, 2012 at 9:08 PM, Oleg Nesterov <oleg@...hat.com> wrote:
> Once again. You have the task_struct *task. It exits,
> but task->thread_group->next still points to another thread T. Now suppose
> that T exits too. But task->thread_group->next was not changed, it still
> points to T. RCU grace period passes, T is freed.
>
> After that you take rcu_read_lock(), but it is too late! >next points to
> the already freed/reused memory. How can list_first_entry_rcu() help?

Ahh, I completely misunderstood your point. Thanks for the detailed explanation.

> And. Imho it is not good to have the (afaics exactly?) same code in
> mm/nommu.c, even with the same names. Why it is not possible to make
> a single definition?

Yes it is the same code. I put the code in both memory.c and nommu.c
because I thought they fit in there logically. I can find a common
place for it.



-- 
Siddhesh Poyarekar
http://siddhesh.in
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/