workqueue: kasan: record workqueue stack

Patch series "kasan: add workqueue stack for generic KASAN", v5.

Syzbot reports many UAF issues for workqueue, see [1].

In some of these access/allocation happened in process_one_work(), we
see the free stack is useless in KASAN report, it doesn't help
programmers to solve UAF for workqueue issue.

This patchset improves KASAN reports by making them to have workqueue
queueing stack.  It is useful for programmers to solve use-after-free or
double-free memory issue.

Generic KASAN also records the last two workqueue stacks and prints them
in KASAN report.  It is only suitable for generic KASAN.

[1] https://groups.google.com/g/syzkaller-bugs/search?q=%22use-after-free%22+process_one_work
[2] https://bugzilla.kernel.org/show_bug.cgi?id=198437

This patch (of 4):

When analyzing 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.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Walter Wu <[email protected]>
Suggested-by: Marco Elver <[email protected]>
Acked-by: Marco Elver <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Reviewed-by: Dmitry Vyukov <[email protected]>
Reviewed-by: Andrey Konovalov <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Lai Jiangshan <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Matthias Brugger <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

kernel/workqueue.c

@@ -1327,6 +1327,9 @@ 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);