[PATCH v2 5/6] kasan: add tests for workqueue stack recording

[Walter Wu]

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...@mediatek.com>
Cc: Andrey Ryabinin <aryabi...@virtuozzo.com>
Cc: Dmitry Vyukov <dvyu...@google.com>
Cc: Alexander Potapenko <gli...@google.com>
Cc: Matthias Brugger <matthias....@gmail.com>
Cc: Andrey Konovalov <andreyk...@google.com>
---
 lib/test_kasan.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 2bd61674c7a3..7293a55ff51c 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -845,6 +845,34 @@ static noinline void __init kasan_timer_uaf(void)
        ((volatile struct timer_list *)timer)->expires;
 }
 
+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 kmalloc_tests_init(void)
 {
        /*
@@ -894,6 +922,7 @@ static int __init kmalloc_tests_init(void)
        vmalloc_oob();
        kasan_rcu_uaf();
        kasan_timer_uaf();
+       kasan_workqueue_uaf();
 
        kasan_restore_multi_shot(multishot);
 
-- 
2.18.0