Messages in this thread | | | From | tanxiaofei <> | Subject | [Question] null pointer risk of kernel workqueue | Date | Sat, 23 Sep 2017 17:04:24 +0800 |
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Hi Tejun & Jiangshan,
I find an null pointer risk in the code of workqueue. Here is description:
If draining, __queue_work() will call the function is_chained_work() to do some checks. In is_chained_work(), worker->current_pwq is used directly. It should be not safe. http://elixir.free-electrons.com/linux/latest/source/kernel/workqueue.c#L1384
If you check the thread function of this worker, worker_thread(), you will find worker->current_pwq is null when one work is done or ready to be processed. This issue may happen only if we queue work during executing drain_workqueue(). http://elixir.free-electrons.com/linux/latest/source/kernel/workqueue.c#L2173
There are very few places to call drain_workqueue() in the whole linux kernel. I think that's why no one noticed this risk.
Xiaofei Tan _______________________________________________ linuxarm mailing list linuxarm@huawei.com http://rnd-openeuler.huawei.com/mailman/listinfo/linuxarm
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