| From cef572ad9bd7f85035ba8272e5352040e8be0152 Mon Sep 17 00:00:00 2001 |
| From: Li Bin <huawei.libin@huawei.com> |
| Date: Sat, 28 Oct 2017 11:07:28 +0800 |
| Subject: workqueue: Fix NULL pointer dereference |
| |
| From: Li Bin <huawei.libin@huawei.com> |
| |
| 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 <tanxiaofei@huawei.com> |
| Signed-off-by: Li Bin <huawei.libin@huawei.com> |
| Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com> |
| Signed-off-by: Tejun Heo <tj@kernel.org> |
| Fixes: 8d03ecfe4718 ("workqueue: reimplement is_chained_work() using current_wq_worker()") |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| 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 <linux/workqueue.h> |
| #include <linux/kthread.h> |
| +#include <linux/preempt.h> |
| |
| 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; |
| } |