[SCSI] Fix VPD inquiry page wrapper

Fix two bugs in the VPD page wrapper:

    - Don't return failure if the user asked for page 0

    - The end of buffer check failed to account for the page header size
      and consequently didn't work
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Stable Tree <stable@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/scsi.c

@@ -1046,13 +1046,13 @@ int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
 
 	/* If the user actually wanted this page, we can skip the rest */
 	if (page == 0)
-		return -EINVAL;
+		return 0;
 
 	for (i = 0; i < min((int)buf[3], buf_len - 4); i++)
 		if (buf[i + 4] == page)
 			goto found;
 
-	if (i < buf[3] && i > buf_len)
+	if (i < buf[3] && i >= buf_len - 4)
 		/* ran off the end of the buffer, give us benefit of doubt */
 		goto found;
 	/* The device claims it doesn't support the requested page */