Messages in this thread | | | From | Lai Jiangshan <> | Date | Sun, 29 Oct 2017 22:48:00 +0800 | Subject | Re: [PATCH v2] workqueue: Fix NULL pointer dereference |
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On Sat, Oct 28, 2017 at 11:07 AM, Li Bin <huawei.libin@huawei.com> wrote: > 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>
> --- > 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 <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; > } > -- > 1.7.12.4 >
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