[PATCH v2] mtd: rawnand: tegra: check bounds of die_nr properly

[Marcel Ziswiler]

From: Stefan Agner <ste...@agner.ch>

The Tegra driver currently only support a single chip select, hence
check boundaries accordingly. This fixes a off by one issue catched
with Smatch:
    drivers/mtd/nand/raw/tegra_nand.c:476 tegra_nand_select_chip()
    warn: array off by one? 'nand->cs[die_nr]'

Also warn in case the stack asks for a chip select we currently do
not support.

Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
Signed-off-by: Stefan Agner <ste...@agner.ch>
Signed-off-by: Miquel Raynal <miquel.ray...@bootlin.com>
Signed-off-by: Marcel Ziswiler <marcel.ziswi...@toradex.com>

---

Changes in v2:
- Fixed comparison between signed integer die_nr and unsigned ARRAY_SIZE.

 drivers/mtd/nand/raw/tegra_nand.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/raw/tegra_nand.c 
b/drivers/mtd/nand/raw/tegra_nand.c
index 9f7de36be893..56c0aa1bc81f 100644
--- a/drivers/mtd/nand/raw/tegra_nand.c
+++ b/drivers/mtd/nand/raw/tegra_nand.c
@@ -468,7 +468,9 @@ static void tegra_nand_select_chip(struct mtd_info *mtd, 
int die_nr)
        struct tegra_nand_chip *nand = to_tegra_chip(chip);
        struct tegra_nand_controller *ctrl = to_tegra_ctrl(chip->controller);
 
-       if (die_nr < 0 || die_nr > 1) {
+       WARN_ON(die_nr >= (int)ARRAY_SIZE(nand->cs));
+
+       if (die_nr < 0 || die_nr > 0) {
                ctrl->cur_cs = -1;
                return;
        }
-- 
2.14.4