Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755785Ab0DVT1e (ORCPT ); Thu, 22 Apr 2010 15:27:34 -0400 Received: from kroah.org ([198.145.64.141]:37119 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755475Ab0DVT13 (ORCPT ); Thu, 22 Apr 2010 15:27:29 -0400 X-Mailbox-Line: From gregkh@kvm.kroah.org Thu Apr 22 12:09:07 2010 Message-Id: <20100422190907.864799567@kvm.kroah.org> User-Agent: quilt/0.48-4.4 Date: Thu, 22 Apr 2010 12:07:36 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Oleg Nesterov Subject: [005/197] oom: fix the unsafe usage of badness() in proc_oom_score() In-Reply-To: <20100422191857.GA13268@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1937 Lines: 58 2.6.32-stable review patch. If anyone has any objections, please let us know. ------------------ From: Oleg Nesterov commit b95c35e76b29ba812e5dabdd91592e25ec640e93 upstream. proc_oom_score(task) has a reference to task_struct, but that is all. If this task was already released before we take tasklist_lock - we can't use task->group_leader, it points to nowhere - it is not safe to call badness() even if this task is ->group_leader, has_intersects_mems_allowed() assumes it is safe to iterate over ->thread_group list. - even worse, badness() can hit ->signal == NULL Add the pid_alive() check to ensure __unhash_process() was not called. Also, use "task" instead of task->group_leader. badness() should return the same result for any sub-thread. Currently this is not true, but this should be changed anyway. Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/proc/base.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -442,12 +442,13 @@ static const struct file_operations proc unsigned long badness(struct task_struct *p, unsigned long uptime); static int proc_oom_score(struct task_struct *task, char *buffer) { - unsigned long points; + unsigned long points = 0; struct timespec uptime; do_posix_clock_monotonic_gettime(&uptime); read_lock(&tasklist_lock); - points = badness(task->group_leader, uptime.tv_sec); + if (pid_alive(task)) + points = badness(task, uptime.tv_sec); read_unlock(&tasklist_lock); return sprintf(buffer, "%lu\n", points); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/