linux-kernel - Re: yama_ptrace_access_check(): possible recursive locking detected

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Message-ID: <20120726154144.GA20964@redhat.com>
Date:	Thu, 26 Jul 2012 17:41:44 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Fengguang Wu <fengguang.wu@...el.com>
Cc:	Kees Cook <keescook@...omium.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: yama_ptrace_access_check(): possible recursive locking detected

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;

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