From: Sebastian Ott <sebott@xxxxxxxxxxxxxxxxxx>
Ensure to always hold an extra device reference for scheduling a
subchannel deregistration, by moving the get_device to
ccw_device_schedule_sch_unregister. This fixes an use after free
error in ccw_device_call_sch_unregister where put_device was called
on an already freed device structure.
Signed-off-by: Sebastian Ott <sebott@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
---
drivers/s390/cio/device.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)
Index: quilt-2.6/drivers/s390/cio/device.c
===================================================================
--- quilt-2.6.orig/drivers/s390/cio/device.c
+++ quilt-2.6/drivers/s390/cio/device.c
@@ -333,15 +333,15 @@ ccw_device_remove_disconnected(struct cc
* Forced offline in disconnected state means
* 'throw away device'.
*/
- /* Get cdev reference for workqueue processing. */
- if (!get_device(&cdev->dev))
- return;
if (ccw_device_is_orphan(cdev)) {
/*
* Deregister ccw device.
* Unfortunately, we cannot do this directly from the
* attribute method.
*/
+ /* Get cdev reference for workqueue processing. */
+ if (!get_device(&cdev->dev))
+ return;
spin_lock_irqsave(cdev->ccwlock, flags);
cdev->private->state = DEV_STATE_NOT_OPER;
spin_unlock_irqrestore(cdev->ccwlock, flags);
@@ -1032,6 +1032,9 @@ static void ccw_device_call_sch_unregist
void ccw_device_schedule_sch_unregister(struct ccw_device *cdev)
{
+ /* Get cdev reference for workqueue processing. */
+ if (!get_device(&cdev->dev))
+ return;
PREPARE_WORK(&cdev->private->kick_work,
ccw_device_call_sch_unregister);
queue_work(slow_path_wq, &cdev->private->kick_work);
@@ -1052,9 +1055,6 @@ io_subchannel_recog_done(struct ccw_devi
/* Device did not respond in time. */
case DEV_STATE_NOT_OPER:
cdev->private->flags.recog_done = 1;
- /* Remove device found not operational. */
- if (!get_device(&cdev->dev))
- break;
ccw_device_schedule_sch_unregister(cdev);
if (atomic_dec_and_test(&ccw_device_init_count))
wake_up(&ccw_device_init_wq);
@@ -1565,8 +1565,6 @@ static int purge_fn(struct device *dev,
spin_unlock_irq(cdev->ccwlock);
if (!unreg)
goto out;
- if (!get_device(&cdev->dev))
- goto out;
CIO_MSG_EVENT(3, "ccw: purging 0.%x.%04x\n", priv->dev_id.ssid,
priv->dev_id.devno);
ccw_device_schedule_sch_unregister(cdev);
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
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