Fix USB CB/CBI storage devices with CONFIG_VMAP_STACK=y

commit 2ce9d227 upstream.

Some code (all error handling) submits CDBs that are allocated
on the stack.  This breaks with CB/CBI code that tries to create
URB directly from SCSI command buffer - which happens to be in
vmalloced memory with vmalloced kernel stacks.

Let's make copy of the command in usb_stor_CB_transport.
Signed-off-by: Petr Vandrovec <petr@vandrovec.name>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

drivers/usb/storage/transport.c

@@ -919,10 +919,15 @@ int usb_stor_CB_transport(struct scsi_cmnd *srb, struct us_data *us)
 
 	/* COMMAND STAGE */
 	/* let's send the command via the control pipe */
+	/*
+	 * Command is sometime (f.e. after scsi_eh_prep_cmnd) on the stack.
+	 * Stack may be vmallocated.  So no DMA for us.  Make a copy.
+	 */
+	memcpy(us->iobuf, srb->cmnd, srb->cmd_len);
 	result = usb_stor_ctrl_transfer(us, us->send_ctrl_pipe,
 				      US_CBI_ADSC, 
 				      USB_TYPE_CLASS | USB_RECIP_INTERFACE, 0, 
-				      us->ifnum, srb->cmnd, srb->cmd_len);
+				      us->ifnum, us->iobuf, srb->cmd_len);
 
 	/* check the return code for the command */
 	usb_stor_dbg(us, "Call to usb_stor_ctrl_transfer() returned %d\n",