[PATCH v2 2/6] workqueue: kasan: record workqueue stack

[Walter Wu <walter-zh.wu@mediatek.com>]

Records the last two enqueuing work call stacks in order to print them
in KASAN report. It is useful for programmers to solve use-after-free
or double-free memory workqueue issue.

For workqueue it has turned out to be useful to record the enqueuing
work call stacks. Because user can see KASAN report to determine
whether it is root cause. They don't need to enable debugobjects,
but they have a chance to find out the root cause.

Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
Suggested-by: Marco Elver <elver@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
---

v2:
- Thanks for Marco suggestion.
- Remove unnecessary code
- reuse kasan_record_aux_stack() and aux_stack
  to record timer and workqueue stack

---

 kernel/workqueue.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index c41c3c17b86a..5fea7dc9180f 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1324,6 +1324,9 @@ static void insert_work(struct pool_workqueue *pwq, struct work_struct *work,
 {
 	struct worker_pool *pool = pwq->pool;
 
+	/* record the work call stack in order to print it in KASAN reports */
+	kasan_record_aux_stack(work);
+
 	/* we own @work, set data and link */
 	set_work_pwq(work, pwq, extra_flags);
 	list_add_tail(&work->entry, head);
-- 
2.18.0