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rtc: fix use-after-free on device removal 

If the irqwork is still scheduled or running while the RTC device is
removed, a use-after-free occurs in rtc_timer_do_work().  Cleanup the
timerqueue and ensure the work is stopped to fix this.

 BUG: KASAN: use-after-free in mutex_lock+0x94/0x110
 Write of size 8 at addr ffffff801d846338 by task kworker/3:1/41

 Workqueue: events rtc_timer_do_work
 Call trace:
  mutex_lock+0x94/0x110
  rtc_timer_do_work+0xec/0x630
  process_one_work+0x5fc/0x1344
  ...

 Allocated by task 551:
  kmem_cache_alloc_trace+0x384/0x6e0
  devm_rtc_allocate_device+0xf0/0x574
  devm_rtc_device_register+0x2c/0x12c
  ...

 Freed by task 572:
  kfree+0x114/0x4d0
  rtc_device_release+0x64/0x80
  device_release+0x8c/0x1f4
  kobject_put+0x1c4/0x4b0
  put_device+0x20/0x30
  devm_rtc_release_device+0x1c/0x30
  devm_action_release+0x54/0x90
  release_nodes+0x124/0x310
  devres_release_group+0x170/0x240
  i2c_device_remove+0xd8/0x314
  ...

 Last potentially related work creation:
  insert_work+0x5c/0x330
  queue_work_on+0xcc/0x154
  rtc_set_time+0x188/0x5bc
  rtc_dev_ioctl+0x2ac/0xbd0
  ...

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20211210160951.7718-1-vincent.whitchurch@axis.com
This commit is contained in:
Vincent Whitchurch 2021-12-10 17:09:51 +01:00 committed by Alexandre Belloni
parent e783362eb5
commit c8fa17d9f0
1 changed files with 9 additions and 0 deletions
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9
drivers/rtc/class.c
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@ -26,6 +26,15 @@ struct class *rtc_class;
static void rtc_device_release(struct device *dev)
{
struct rtc_device *rtc = to_rtc_device(dev);
struct timerqueue_head *head = &rtc->timerqueue;
struct timerqueue_node *node;
mutex_lock(&rtc->ops_lock);
while ((node = timerqueue_getnext(head)))
timerqueue_del(head, node);
mutex_unlock(&rtc->ops_lock);
cancel_work_sync(&rtc->irqwork);
ida_simple_remove(&rtc_ida, rtc->id);
mutex_destroy(&rtc->ops_lock);