Re: [PATCH v5 3/4] lib/test_kasan.c: add workqueue test case

Re: [PATCH v5 3/4] lib/test_kasan.c: add workqueue test case

[Marco Elver]

On Thu, 3 Dec 2020 at 03:27, Walter Wu <walter-zh.wu@mediatek.com> wrote:
>
> Adds a test to verify workqueue stack recording and print it in
> KASAN report.
>
> The KASAN report was as follows(cleaned up slightly):
>
>  BUG: KASAN: use-after-free in kasan_workqueue_uaf
>
>  Freed by task 54:
>   kasan_save_stack+0x24/0x50
>   kasan_set_track+0x24/0x38
>   kasan_set_free_info+0x20/0x40
>   __kasan_slab_free+0x10c/0x170
>   kasan_slab_free+0x10/0x18
>   kfree+0x98/0x270
>   kasan_workqueue_work+0xc/0x18
>
>  Last potentially related work creation:
>   kasan_save_stack+0x24/0x50
>   kasan_record_wq_stack+0xa8/0xb8
>   insert_work+0x48/0x288
>   __queue_work+0x3e8/0xc40
>   queue_work_on+0xf4/0x118
>   kasan_workqueue_uaf+0xfc/0x190
>
> Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
> Acked-by: Marco Elver <elver@google.com>
> Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
> Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Matthias Brugger <matthias.bgg@gmail.com>
> ---
>
> v4:
> - testcase has merge conflict, so that rebase onto the KASAN-KUNIT
>
> ---
>  lib/test_kasan_module.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
>
> diff --git a/lib/test_kasan_module.c b/lib/test_kasan_module.c
> index 2d68db6ae67b..62a87854b120 100644
> --- a/lib/test_kasan_module.c
> +++ b/lib/test_kasan_module.c
> @@ -91,6 +91,34 @@ static noinline void __init kasan_rcu_uaf(void)
>         call_rcu(&global_rcu_ptr->rcu, kasan_rcu_reclaim);
>  }
>
> +static noinline void __init kasan_workqueue_work(struct work_struct *work)
> +{
> +       kfree(work);
> +}
> +
> +static noinline void __init kasan_workqueue_uaf(void)
> +{
> +       struct workqueue_struct *workqueue;
> +       struct work_struct *work;
> +
> +       workqueue = create_workqueue("kasan_wq_test");
> +       if (!workqueue) {
> +               pr_err("Allocation failed\n");
> +               return;
> +       }
> +       work = kmalloc(sizeof(struct work_struct), GFP_KERNEL);
> +       if (!work) {
> +               pr_err("Allocation failed\n");
> +               return;
> +       }
> +
> +       INIT_WORK(work, kasan_workqueue_work);
> +       queue_work(workqueue, work);
> +       destroy_workqueue(workqueue);
> +
> +       pr_info("use-after-free on workqueue\n");
> +       ((volatile struct work_struct *)work)->data;
> +}
>
>  static int __init test_kasan_module_init(void)
>  {
> @@ -102,6 +130,7 @@ static int __init test_kasan_module_init(void)
>
>         copy_user_test();
>         kasan_rcu_uaf();
> +       kasan_workqueue_uaf();


Why can't this go into the KUnit based KASAN test?