[PATCH 3.5 43/71] [SCSI] storvsc: NULL pointer dereference fix

[Luis Henriques]

3.5.7.33 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ales Novak <alnovak at suse.cz>

commit b12bb60d6c350b348a4e1460cd68f97ccae9822e upstream.

If the initialization of storvsc fails, the storvsc_device_destroy()
causes NULL pointer dereference.

storvsc_bus_scan()
  scsi_scan_target()
    __scsi_scan_target()
      scsi_probe_and_add_lun(hostdata=NULL)
        scsi_alloc_sdev(hostdata=NULL)

	  sdev->hostdata = hostdata

	  now the host allocation fails

          __scsi_remove_device(sdev)

	  calls sdev->host->hostt->slave_destroy() ==
	  storvsc_device_destroy(sdev)
	    access of sdev->hostdata->request_mempool

Signed-off-by: Ales Novak <alnovak at suse.cz>
Signed-off-by: Thomas Abraham <tabraham at suse.com>
Reviewed-by: Jiri Kosina <jkosina at suse.cz>
Acked-by: K. Y. Srinivasan <kys at microsoft.com>
Signed-off-by: James Bottomley <JBottomley at Parallels.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/scsi/storvsc_drv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 9f4e560..65f566b 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1141,6 +1141,9 @@ static void storvsc_device_destroy(struct scsi_device *sdevice)
 {
 	struct stor_mem_pools *memp = sdevice->hostdata;
 
+	if (!memp)
+		return;
+
 	mempool_destroy(memp->request_mempool);
 	kmem_cache_destroy(memp->request_pool);
 	kfree(memp);
-- 
1.9.1