From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:49306 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751234AbdKMM5v (ORCPT ); Mon, 13 Nov 2017 07:57:51 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xiaofei Tan , Li Bin , Lai Jiangshan , Tejun Heo Subject: [PATCH 4.4 33/56] workqueue: Fix NULL pointer dereference Date: Mon, 13 Nov 2017 13:55:57 +0100 Message-Id: <20171113125601.894976754@linuxfoundation.org> In-Reply-To: <20171113125557.613444087@linuxfoundation.org> References: <20171113125557.613444087@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Li Bin commit cef572ad9bd7f85035ba8272e5352040e8be0152 upstream. 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 Reviewed-by: Lai Jiangshan Signed-off-by: Tejun Heo Fixes: 8d03ecfe4718 ("workqueue: reimplement is_chained_work() using current_wq_worker()") Signed-off-by: Greg Kroah-Hartman --- kernel/workqueue_internal.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- 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; }