mtd: nand: Error out if cmd_ctrl() is missing

If no user specified chip->select_chip() function is provided, code in
nand_base.c will automatically set this hook to nand_select_chip(),
which in turn depends on chip->cmd_ctrl() hook being valid. Not
providing both of those functions in NAND controller driver (for example
by mistake) will result in a bit cryptic segfault. Same is true for
chip->cmdfunc().

To avoid the above scenario add a check in nand_scan_dent and error out
if cmd_ctrl() is not provided.

Suggested-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Suggested-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 53ea79628ddeb2fb6ca7fb5ed86d8abef0120fd3..7f742c9c90155f3246f4076ad4cb42bffaf0024c 100644 (file)
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -4140,6 +4140,15 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips,
        if (!mtd->name && mtd->dev.parent)
                mtd->name = dev_name(mtd->dev.parent);
 
+       if ((!chip->cmdfunc || !chip->select_chip) && !chip->cmd_ctrl) {
+               /*
+                * Default functions assigned for chip_select() and
+                * cmdfunc() both expect cmd_ctrl() to be populated,
+                * so we need to check that that's the case
+                */
+               pr_err("chip.cmd_ctrl() callback is not provided");
+               return -EINVAL;
+       }
        /* Set the default functions */
        nand_set_defaults(chip, chip->options & NAND_BUSWIDTH_16);