[PATCH] usb-storage: catch bad commands

The purpose of this patch is to trap all commands which have a bogus
request_bufflen.  Much logic is devoted to calculating the proper length of
the transfer, but according to discussions I've had on linux-scsi, this is
really a bug in whatever is originating the bad command.

Hopefully, after people use this patch for a while, we'll eliminate all the
offending sources and can remove quite a bit of logic from the driver.

drivers/usb/storage/transport.c

@@ -344,6 +344,12 @@ unsigned int usb_stor_transfer_length(Scsi_Cmnd *srb)
 			   len = srb->request_bufflen;
 	   }
 
+	/* According to the linux-scsi people, any command sent which
+	 * violates this invariant is a bug.  In the hopes of removing
+	 * all the complex logic above, let's find them and eliminate them.
+	 */
+	BUG_ON(len != srb->request_bufflen);
+
 	return len;
 }