[PATCH v5 1/4] workqueue: kasan: record workqueue stack

[Walter Wu]

When analyze use-after-free or double-free issue, recording the
enqueuing work stacks is helpful to preserve usage history which
potentially gives a hint about the affected code.

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 at mediatek.com>
Suggested-by: Marco Elver <elver at google.com>
Acked-by: Marco Elver <elver at google.com>
Acked-by: Tejun Heo <tj at kernel.org>
Reviewed-by: Dmitry Vyukov <dvyukov at google.com>
Reviewed-by: Andrey Konovalov <andreyknvl at google.com>
Cc: Andrey Ryabinin <aryabinin at virtuozzo.com>
Cc: Alexander Potapenko <glider at google.com>
Cc: Lai Jiangshan <jiangshanlai at 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..9dd65ac60d6e 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