From: Walter Wu <walter-zh.wu@xxxxxxxxxxxx> Subject: 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/20201203022148.29754-1-walter-zh.wu@xxxxxxxxxxxx Link: https://lkml.kernel.org/r/20201203022442.30006-1-walter-zh.wu@xxxxxxxxxxxx Signed-off-by: Walter Wu <walter-zh.wu@xxxxxxxxxxxx> Suggested-by: Marco Elver <elver@xxxxxxxxxx> Acked-by: Marco Elver <elver@xxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx> Cc: Marco Elver <elver@xxxxxxxxxx> Cc: Matthias Brugger <matthias.bgg@xxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/workqueue.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/workqueue.c~workqueue-kasan-record-workqueue-stack +++ a/kernel/workqueue.c @@ -1327,6 +1327,9 @@ static void insert_work(struct pool_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); _
