linux-kernel - [PATCH] iio: trigger: sysfs: fix use-after-free on remove

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Date:   Thu, 19 May 2022 11:19:25 +0200
From:   Vincent Whitchurch <vincent.whitchurch@...s.com>
To:     Jonathan Cameron <jic23@...nel.org>
CC:     <kernel@...s.com>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] iio: trigger: sysfs: fix use-after-free on remove

Ensure that the irq_work has completed before the trigger is freed.

 ==================================================================
 BUG: KASAN: use-after-free in irq_work_run_list
 Read of size 8 at addr 0000000064702248 by task python3/25

 Call Trace:
  irq_work_run_list
  irq_work_tick
  update_process_times
  tick_sched_handle
  tick_sched_timer
  __hrtimer_run_queues
  hrtimer_interrupt

 Allocated by task 25:
  kmem_cache_alloc_trace
  iio_sysfs_trig_add
  dev_attr_store
  sysfs_kf_write
  kernfs_fop_write_iter
  new_sync_write
  vfs_write
  ksys_write
  sys_write

 Freed by task 25:
  kfree
  iio_sysfs_trig_remove
  dev_attr_store
  sysfs_kf_write
  kernfs_fop_write_iter
  new_sync_write
  vfs_write
  ksys_write
  sys_write

 ==================================================================

Fixes: e64e7d5c8c86e ("iio:trigger:sysfs Move out of staging.")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>
---
 drivers/iio/trigger/iio-trig-sysfs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iio/trigger/iio-trig-sysfs.c b/drivers/iio/trigger/iio-trig-sysfs.c
index 2a4b75897910..3d911c24b265 100644
--- a/drivers/iio/trigger/iio-trig-sysfs.c
+++ b/drivers/iio/trigger/iio-trig-sysfs.c
@@ -191,6 +191,7 @@ static int iio_sysfs_trigger_remove(int id)
 	}
 
 	iio_trigger_unregister(t->trig);
+	irq_work_sync(&t->work);
 	iio_trigger_free(t->trig);
 
 	list_del(&t->l);
-- 
2.34.1