diff options
authorLi Bin <>2017-10-28 11:07:28 +0800
committerTejun Heo <>2017-10-30 07:56:01 -0700
commitcef572ad9bd7f85035ba8272e5352040e8be0152 (patch)
parent692b48258dda7c302e777d7d5f4217244478f1f6 (diff)
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 <> 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()") Cc: # v3.9+
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/workqueue_internal.h b/kernel/workqueue_internal.h
index 8635417c587b..29fa81f0f51a 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;