Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754077AbXKXQ7W (ORCPT ); Sat, 24 Nov 2007 11:59:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752550AbXKXQ7P (ORCPT ); Sat, 24 Nov 2007 11:59:15 -0500 Received: from x346.tv-sign.ru ([89.108.83.215]:47523 "EHLO mail.screens.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752497AbXKXQ7O (ORCPT ); Sat, 24 Nov 2007 11:59:14 -0500 Date: Sat, 24 Nov 2007 19:59:34 +0300 From: Oleg Nesterov To: Andrew Morton Cc: Pavel Emelyanov , Roland McGrath , linux-kernel@vger.kernel.org Subject: [PATCH] wait_task_continued/zombie: don't use task_pid_nr_ns() lockless Message-ID: <20071124165934.GA8033@tv-sign.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2358 Lines: 70 Surprise, other 2 wait_task_() functions also abuse task_pid_nr_ns(). May cause read-after-free or report nr == 0 in wait_task_continued(). wait_task_zombie() doesn't have this problem, but still it is better to cache pid_t rather than call task_pid_nr_ns() 3 times on the saved pid_namespace. Signed-off-by: Oleg Nesterov --- PT/kernel/exit.c~PID 2007-11-24 18:17:20.000000000 +0300 +++ PT/kernel/exit.c 2007-11-24 19:28:11.000000000 +0300 @@ -1186,12 +1186,9 @@ static int wait_task_zombie(struct task_ { unsigned long state; int retval, status, traced; - struct pid_namespace *ns; - - ns = current->nsproxy->pid_ns; + pid_t pid = task_pid_nr_ns(p, current->nsproxy->pid_ns); if (unlikely(noreap)) { - pid_t pid = task_pid_nr_ns(p, ns); uid_t uid = p->uid; int exit_code = p->exit_code; int why, status; @@ -1310,11 +1307,11 @@ static int wait_task_zombie(struct task_ retval = put_user(status, &infop->si_status); } if (!retval && infop) - retval = put_user(task_pid_nr_ns(p, ns), &infop->si_pid); + retval = put_user(pid, &infop->si_pid); if (!retval && infop) retval = put_user(p->uid, &infop->si_uid); if (!retval) - retval = task_pid_nr_ns(p, ns); + retval = pid; if (traced) { write_lock_irq(&tasklist_lock); @@ -1433,7 +1430,6 @@ static int wait_task_continued(struct ta int retval; pid_t pid; uid_t uid; - struct pid_namespace *ns; if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) return 0; @@ -1448,8 +1444,7 @@ static int wait_task_continued(struct ta p->signal->flags &= ~SIGNAL_STOP_CONTINUED; spin_unlock_irq(&p->sighand->siglock); - ns = current->nsproxy->pid_ns; - pid = task_pid_nr_ns(p, ns); + pid = task_pid_nr_ns(p, current->nsproxy->pid_ns); uid = p->uid; get_task_struct(p); read_unlock(&tasklist_lock); @@ -1460,7 +1455,7 @@ static int wait_task_continued(struct ta if (!retval && stat_addr) retval = put_user(0xffff, stat_addr); if (!retval) - retval = task_pid_nr_ns(p, ns); + retval = pid; } else { retval = wait_noreap_copyout(p, pid, uid, CLD_CONTINUED, SIGCONT, - 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/