mtd: ensure index is positive

The index is signed, make sure it is not negative
when we read the array element.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/mtd/nand/fsl_upm.c b/drivers/mtd/nand/fsl_upm.c
index d120cd8d7267..071a60cb4204 100644
--- a/drivers/mtd/nand/fsl_upm.c
+++ b/drivers/mtd/nand/fsl_upm.c
@@ -112,7 +112,7 @@ static void fun_select_chip(struct mtd_info *mtd, int mchip_nr)
 
         if (mchip_nr == -1) {
                 chip->cmd_ctrl(mtd, NAND_CMD_NONE, 0 | NAND_CTRL_CHANGE);
-        } else if (mchip_nr >= 0) {
+        } else if (mchip_nr >= 0 && mchip_nr < NAND_MAX_CHIPS) {
                 fun->mchip_number = mchip_nr;
                 chip->IO_ADDR_R = fun->io_base + fun->mchip_offsets[mchip_nr];
                 chip->IO_ADDR_W = chip->IO_ADDR_R;