From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751273AbdJ1DQe (ORCPT ); Fri, 27 Oct 2017 23:16:34 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:34076 "EHLO huawei.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1750851AbdJ1DQd (ORCPT ); Fri, 27 Oct 2017 23:16:33 -0400 From: Li Bin To: Tejun Heo , Lai Jiangshan CC: , , , Subject: [PATCH v2] workqueue: Fix NULL pointer dereference Date: Sat, 28 Oct 2017 11:07:28 +0800 Message-ID: <1509160048-34939-1-git-send-email-huawei.libin@huawei.com> X-Mailer: git-send-email 1.7.12.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.102.37] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When queue_work() is used in irq (not in task context), there is a potential case that trigger NULL pointer dereference. ---------------------------------------------------------------- worker_thread() |-spin_lock_irq() |-process_one_work() |-worker->current_pwq = pwq |-spin_unlock_irq() |-worker->current_func(work) |-spin_lock_irq() |-worker->current_pwq = NULL |-spin_unlock_irq() //interrupt here |-irq_handler |-__queue_work() //assuming that the wq is draining |-is_chained_work(wq) |-current_wq_worker() //Here, 'current' is the interrupted worker! |-current->current_pwq is NULL here! |-schedule() ---------------------------------------------------------------- Avoid it by checking for task context in current_wq_worker(), and if not in task context, we shouldn't use the 'current' to check the condition. Reported-by: Xiaofei Tan Signed-off-by: Li Bin --- kernel/workqueue_internal.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/workqueue_internal.h b/kernel/workqueue_internal.h index 8635417..29fa81f 100644 --- a/kernel/workqueue_internal.h +++ b/kernel/workqueue_internal.h @@ -9,6 +9,7 @@ #include #include +#include struct worker_pool; @@ -59,7 +60,7 @@ struct worker { */ static inline struct worker *current_wq_worker(void) { - if (current->flags & PF_WQ_WORKER) + if (in_task() && (current->flags & PF_WQ_WORKER)) return kthread_data(current); return NULL; } -- 1.7.12.4