Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755430Ab0KYBKA (ORCPT ); Wed, 24 Nov 2010 20:10:00 -0500 Received: from mx1.redhat.com ([209.132.183.28]:9451 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751367Ab0KYBJ7 (ORCPT ); Wed, 24 Nov 2010 20:09:59 -0500 Date: Wed, 24 Nov 2010 20:09:48 -0500 From: Dave Jones To: Linux Kernel Cc: Andrew Morton Subject: rcu_read_lock/unlock protect find_task_by_vpid call in posix_cpu_timer_create Message-ID: <20101125010948.GA1371@redhat.com> Mail-Followup-To: Dave Jones , Linux Kernel , Andrew Morton MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1908 Lines: 53 =================================================== [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- kernel/pid.c:419 invoked rcu_dereference_check() without protection! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 1 1 lock held by scrashme/20820: #0: (tasklist_lock){.?.?..}, at: [] posix_cpu_timer_create+0x50/0xee stack backtrace: Pid: 20820, comm: scrashme Not tainted 2.6.37-rc3+ #7 Call Trace: [] lockdep_rcu_dereference+0x9d/0xa5 [] find_task_by_pid_ns+0x44/0x5d [] find_task_by_vpid+0x22/0x24 [] posix_cpu_timer_create+0x6e/0xee [] do_cpu_nanosleep+0x83/0x1ad [] posix_cpu_nsleep+0x6d/0xf6 [] ? might_fault+0xa5/0xac [] ? might_fault+0x5c/0xac [] sys_clock_nanosleep+0x7c/0xcb [] system_call_fastpath+0x16/0x1b Signed-off-by: Dave Jones diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index 6842eeb..2658955 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -391,6 +391,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer) INIT_LIST_HEAD(&new_timer->it.cpu.entry); read_lock(&tasklist_lock); + rcu_read_lock(); if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) { if (pid == 0) { p = current; @@ -414,6 +415,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer) } else { ret = -EINVAL; } + rcu_read_unlock(); read_unlock(&tasklist_lock); return ret; -- 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/