mtd: nand: add check for out of page read

When run mtd_oobtest case, there will be one error for step(4),
which turned out it need add one check for out of page read in
nand_do_read_oob just like mtd_do_write_oob did it already.
This commit also fix one typo error for comments in mtd_do_write_oob
Signed-off-by: NJason Liu <r64343@freescale.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/nand_base.c

@@ -1782,6 +1782,13 @@ static int nand_do_read_oob(struct mtd_info *mtd, loff_t from,
 	else
 		len = mtd->oobsize;
 
+	/* Do not allow read past end of page */
+	if ((ops->ooboffs + readlen) > len) {
+		DEBUG(MTD_DEBUG_LEVEL0, "%s: Attempt to read "
+				"past end of page\n", __func__);
+		return -EINVAL;
+	}
+
 	if (unlikely(ops->ooboffs >= len)) {
 		DEBUG(MTD_DEBUG_LEVEL0, "%s: Attempt to start read "
 					"outside oob\n", __func__);
@@ -2377,7 +2384,7 @@ static int nand_do_write_oob(struct mtd_info *mtd, loff_t to,
 		return -EINVAL;
 	}
 
-	/* Do not allow reads past end of device */
+	/* Do not allow write past end of device */
 	if (unlikely(to >= mtd->size ||
 		     ops->ooboffs + ops->ooblen >
 			((mtd->size >> chip->page_shift) -