From: Sebastian Ott Date: Fri, 11 Sep 2009 08:28:20 +0000 (+0200) Subject: [S390] cio: ensure to hold a reference for deferred deregistration X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=be7a2ddce66991c05a1c6ad19790289591e53547;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git [S390] cio: ensure to hold a reference for deferred deregistration 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 Signed-off-by: Martin Schwidefsky --- diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c index 19b4469a3ca4..a7a340b1d713 100644 --- a/drivers/s390/cio/device.c +++ b/drivers/s390/cio/device.c @@ -333,15 +333,15 @@ ccw_device_remove_disconnected(struct ccw_device *cdev) * 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_unregister(struct work_struct *work) 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_device *cdev) /* 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, void *data) 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);