[PATCH v4 0/6] kasan: add workqueue and timer stack for generic KASAN

[Walter Wu]

Syzbot reports many UAF issues for workqueue or timer, see [1] and [2].
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 on workqueue. The same may stand for times.

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

Generic KASAN also records the last two workqueue and timer 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://groups.google.com/g/syzkaller-bugs/search?q=%22use-after-free%22%20expire_timers
[3]https://bugzilla.kernel.org/show_bug.cgi?id=198437

Walter Wu (6):
timer: kasan: record timer stack
workqueue: kasan: record workqueue stack
kasan: print timer and workqueue stack
lib/test_kasan.c: add timer test case
lib/test_kasan.c: add workqueue test case
kasan: update documentation for generic kasan

---
Changes since v3:
- testcases have merge conflict, so that need to
  be rebased onto the KASAN-KUNIT.

Changes since v2:
- modify kasan document to be readable,
  Thanks for Marco suggestion.

Changes since v1:
- Thanks for Marco and Thomas suggestion.
- Remove unnecessary code and fix commit log
- reuse kasan_record_aux_stack() and aux_stack
  to record timer and workqueue stack.
- change the aux stack title for common name.

---
Documentation/dev-tools/kasan.rst |  5 +++--
kernel/time/timer.c               |  3 +++
kernel/workqueue.c                |  3 +++
lib/test_kasan_module.c           | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
mm/kasan/report.c                 |  4 ++--
5 files changed, 66 insertions(+), 4 deletions(-)