[SCSI] storvsc: NULL pointer dereference fix

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@suse.cz>
Signed-off-by: Thomas Abraham <tabraham@suse.com>
Reviewed-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 17d7404272400dd1a76989a3965e0c4b85343036..9969fa1ef7c4ef09ac4fc72c942c5ef72703ae49 100644 (file)
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1419,6 +1419,9 @@ 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);