linux/kernel/workqueue_internal.h
Li Bin cef572ad9b workqueue: Fix NULL pointer dereference
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: 8d03ecfe47 ("workqueue: reimplement is_chained_work() using current_wq_worker()")
Cc: stable@vger.kernel.org # v3.9+
2017-10-30 07:56:01 -07:00

76 lines
2.2 KiB
C

/*
* kernel/workqueue_internal.h
*
* Workqueue internal header file. Only to be included by workqueue and
* core kernel subsystems.
*/
#ifndef _KERNEL_WORKQUEUE_INTERNAL_H
#define _KERNEL_WORKQUEUE_INTERNAL_H
#include <linux/workqueue.h>
#include <linux/kthread.h>
#include <linux/preempt.h>
struct worker_pool;
/*
* The poor guys doing the actual heavy lifting. All on-duty workers are
* either serving the manager role, on idle list or on busy hash. For
* details on the locking annotation (L, I, X...), refer to workqueue.c.
*
* Only to be used in workqueue and async.
*/
struct worker {
/* on idle list while idle, on busy hash table while busy */
union {
struct list_head entry; /* L: while idle */
struct hlist_node hentry; /* L: while busy */
};
struct work_struct *current_work; /* L: work being processed */
work_func_t current_func; /* L: current_work's fn */
struct pool_workqueue *current_pwq; /* L: current_work's pwq */
bool desc_valid; /* ->desc is valid */
struct list_head scheduled; /* L: scheduled works */
/* 64 bytes boundary on 64bit, 32 on 32bit */
struct task_struct *task; /* I: worker task */
struct worker_pool *pool; /* I: the associated pool */
/* L: for rescuers */
struct list_head node; /* A: anchored at pool->workers */
/* A: runs through worker->node */
unsigned long last_active; /* L: last active timestamp */
unsigned int flags; /* X: flags */
int id; /* I: worker id */
/*
* Opaque string set with work_set_desc(). Printed out with task
* dump for debugging - WARN, BUG, panic or sysrq.
*/
char desc[WORKER_DESC_LEN];
/* used only by rescuers to point to the target workqueue */
struct workqueue_struct *rescue_wq; /* I: the workqueue to rescue */
};
/**
* current_wq_worker - return struct worker if %current is a workqueue worker
*/
static inline struct worker *current_wq_worker(void)
{
if (in_task() && (current->flags & PF_WQ_WORKER))
return kthread_data(current);
return NULL;
}
/*
* Scheduler hooks for concurrency managed workqueue. Only to be used from
* sched/core.c and workqueue.c.
*/
void wq_worker_waking_up(struct task_struct *task, int cpu);
struct task_struct *wq_worker_sleeping(struct task_struct *task);
#endif /* _KERNEL_WORKQUEUE_INTERNAL_H */