pinctrl: add checks for empty function names

This is needed as otherwise we can get the following when
dealing with buggy data in a pinmux driver for
pinmux_search_function:

Unable to handle kernel NULL pointer dereference at virtual
address 00000000
...
PC is at strcmp+0xc/0x34
LR is at pinmux_get+0x350/0x8f4
...

As we need pctldev initialized to call ops->list_functions,
let's initialize it before check_ops calls and pass the
pctldev to the check_ops functions. Do this for both pinmux
and pinconf check_ops functions.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 16 insertions, 1 deletions

diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index 3ffa9324ed82..7c3193f7a044 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -889,8 +889,11 @@ void pinmux_disable(struct pinmux *pmx)
 }
 EXPORT_SYMBOL_GPL(pinmux_disable);
 
-int pinmux_check_ops(const struct pinmux_ops *ops)
+int pinmux_check_ops(struct pinctrl_dev *pctldev)
 {
+	const struct pinmux_ops *ops = pctldev->desc->pmxops;
+	unsigned selector = 0;
+
 	/* Check that we implement required operations */
 	if (!ops->list_functions ||
 	    !ops->get_function_name ||
@@ -899,6 +902,18 @@ int pinmux_check_ops(const struct pinmux_ops *ops)
 	    !ops->disable)
 		return -EINVAL;
 
+	/* Check that all functions registered have names */
+	while (ops->list_functions(pctldev, selector) >= 0) {
+		const char *fname = ops->get_function_name(pctldev,
+							   selector);
+		if (!fname) {
+			pr_err("pinmux ops has no name for function%u\n",
+				selector);
+			return -EINVAL;
+		}
+		selector++;
+	}
+
 	return 0;
 }