From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753865Ab2HOSmJ (ORCPT ); Wed, 15 Aug 2012 14:42:09 -0400 Received: from smtp.outflux.net ([198.145.64.163]:54750 "EHLO smtp.outflux.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751448Ab2HOSmI (ORCPT ); Wed, 15 Aug 2012 14:42:08 -0400 Date: Wed, 15 Aug 2012 11:41:55 -0700 From: Kees Cook To: linux-kernel@vger.kernel.org Cc: James Morris , Fengguang Wu , Oleg Nesterov , Kees Cook , John Johansen , linux-security-module@vger.kernel.org Subject: [PATCH v2] Yama: access task_struct->comm directly Message-ID: <20120815184155.GA3666@www.outflux.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-06-14) X-HELO: www.outflux.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The core ptrace access checking routine holds a task lock, and when reporting a failure, Yama takes a separate task lock. To avoid a potential deadlock with two ptracers taking the opposite locks, do not use get_task_comm() and just use ->comm directly since accuracy is not important for the report. Reported-by: Fengguang Wu Suggested-by: Oleg Nesterov CC: stable@vger.kernel.org Signed-off-by: Kees Cook Acked-by: John Johansen --- v2: update with newly added traceme report. --- security/yama/yama_lsm.c | 10 ++-------- 1 files changed, 2 insertions(+), 8 deletions(-) diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c index d51b7c7..0cc99a3 100644 --- a/security/yama/yama_lsm.c +++ b/security/yama/yama_lsm.c @@ -279,12 +279,9 @@ static int yama_ptrace_access_check(struct task_struct *child, } 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; @@ -319,12 +316,9 @@ static int yama_ptrace_traceme(struct task_struct *parent) } if (rc) { - char name[sizeof(current->comm)]; printk_ratelimited(KERN_NOTICE "ptraceme of pid %d was attempted by: %s (pid %d)\n", - current->pid, - get_task_comm(name, parent), - parent->pid); + current->pid, parent->comm, parent->pid); } return rc; -- 1.7.0.4 -- Kees Cook Chrome OS Security