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From: Kees Cook <keescook@chromium.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: yama_ptrace_access_check(): possible recursive locking detected
Date: Mon, 30 Jul 2012 10:00:00 -0700	[thread overview]
Message-ID: <CAGXu5jKEtJ-ySq-PgU7hvzVgnQrJ91pxSALCoMpqJigeNmRzLg@mail.gmail.com> (raw)
In-Reply-To: <20120726154144.GA20964@redhat.com>

On Thu, Jul 26, 2012 at 8:41 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> On 07/26, Fengguang Wu wrote:
>>
>> Here is a recursive lock possibility:
>>
>>         ptrace_may_access()
>> =>        task_lock(task);
>>             yama_ptrace_access_check()
>>               get_task_comm()
>> =>              task_lock(task);
>
> I think yama_ptrace_access_check() can simply use ->comm
>
> Oleg.
>
> --- x/security/yama/yama_lsm.c
> +++ x/security/yama/yama_lsm.c
> @@ -279,12 +279,9 @@ static int yama_ptrace_access_check(stru
>         }
>
>         if (rc) {
> -               char name[sizeof(current->comm)];
>                 printk_ratelimited(KERN_NOTICE
>                         "ptrace of pid %d was attempted by: %s (pid %d)\n",
> -                       child->pid,
> -                       get_task_comm(name, current),
> -                       current->pid);
> +                       child->pid, current->comm, current->pid);
>         }
>
>         return rc;
>

Great catch, thanks! I've sent Oleg's suggestion (with an added
comment) separately.

-Kees

-- 
Kees Cook
Chrome OS Security

  reply	other threads:[~2012-07-30 17:00 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-26 13:47 yama_ptrace_access_check(): possible recursive locking detected Fengguang Wu
2012-07-26 15:41 ` Oleg Nesterov
2012-07-30 17:00   ` Kees Cook [this message]
2012-08-10  1:39 ` Kees Cook
2012-08-10  1:52   ` Fengguang Wu
2012-08-14 21:16     ` Kees Cook
2012-08-15  3:01       ` Fengguang Wu
2012-08-15  5:56         ` Kees Cook
2012-08-15  8:05           ` Peter Zijlstra
2012-08-15 13:01           ` Oleg Nesterov
2012-08-15 14:30             ` Peter Zijlstra
2012-08-15 17:56               ` Oleg Nesterov
2012-08-15 18:09                 ` Kees Cook
2012-08-15 18:17                   ` Oleg Nesterov
2012-08-15 18:30                     ` Kees Cook
2012-08-15 18:44                   ` Alan Cox
2012-08-15 18:43                     ` Kees Cook

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