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>

drivers/pinctrl/core.c

@@ -583,26 +583,6 @@ struct pinctrl_dev *pinctrl_register(struct pinctrl_desc *pctldesc,
 	if (pctldesc->name == NULL)
 		return NULL;
 
-	/* If we're implementing pinmuxing, check the ops for sanity */
-	if (pctldesc->pmxops) {
-		ret = pinmux_check_ops(pctldesc->pmxops);
-		if (ret) {
-			pr_err("%s pinmux ops lacks necessary functions\n",
-			       pctldesc->name);
-			return NULL;
-		}
-	}
-
-	/* If we're implementing pinconfig, check the ops for sanity */
-	if (pctldesc->confops) {
-		ret = pinconf_check_ops(pctldesc->confops);
-		if (ret) {
-			pr_err("%s pin config ops lacks necessary functions\n",
-			       pctldesc->name);
-			return NULL;
-		}
-	}
-
 	pctldev = kzalloc(sizeof(struct pinctrl_dev), GFP_KERNEL);
 	if (pctldev == NULL)
 		return NULL;
@@ -617,6 +597,26 @@ struct pinctrl_dev *pinctrl_register(struct pinctrl_desc *pctldesc,
 	mutex_init(&pctldev->gpio_ranges_lock);
 	pctldev->dev = dev;
 
+	/* If we're implementing pinmuxing, check the ops for sanity */
+	if (pctldesc->pmxops) {
+		ret = pinmux_check_ops(pctldev);
+		if (ret) {
+			pr_err("%s pinmux ops lacks necessary functions\n",
+			       pctldesc->name);
+			goto out_err;
+		}
+	}
+
+	/* If we're implementing pinconfig, check the ops for sanity */
+	if (pctldesc->confops) {
+		ret = pinconf_check_ops(pctldev);
+		if (ret) {
+			pr_err("%s pin config ops lacks necessary functions\n",
+			       pctldesc->name);
+			goto out_err;
+		}
+	}
+
 	/* Register all the pins */
 	pr_debug("try to register %d pins on %s...\n",
 		 pctldesc->npins, pctldesc->name);

drivers/pinctrl/pinconf.c

@@ -205,8 +205,10 @@ int pin_config_group_set(const char *dev_name, const char *pin_group,
 }
 EXPORT_SYMBOL(pin_config_group_set);
 
-int pinconf_check_ops(const struct pinconf_ops *ops)
+int pinconf_check_ops(struct pinctrl_dev *pctldev)
 {
+	const struct pinconf_ops *ops = pctldev->desc->confops;
+
 	/* We must be able to read out pin status */
 	if (!ops->pin_config_get && !ops->pin_config_group_get)
 		return -EINVAL;

drivers/pinctrl/pinconf.h

@@ -13,7 +13,7 @@
 
 #ifdef CONFIG_PINCONF
 
-int pinconf_check_ops(const struct pinconf_ops *ops);
+int pinconf_check_ops(struct pinctrl_dev *pctldev);
 void pinconf_init_device_debugfs(struct dentry *devroot,
 				 struct pinctrl_dev *pctldev);
 int pin_config_get_for_pin(struct pinctrl_dev *pctldev, unsigned pin,
@@ -23,7 +23,7 @@ int pin_config_set_for_pin(struct pinctrl_dev *pctldev, unsigned pin,
 
 #else
 
-static inline int pinconf_check_ops(const struct pinconf_ops *ops)
+static inline int pinconf_check_ops(struct pinctrl_dev *pctldev)
 {
 	return 0;
 }

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;
 }
 

drivers/pinctrl/pinmux.h

@@ -12,7 +12,7 @@
  */
 #ifdef CONFIG_PINMUX
 
-int pinmux_check_ops(const struct pinmux_ops *ops);
+int pinmux_check_ops(struct pinctrl_dev *pctldev);
 void pinmux_init_device_debugfs(struct dentry *devroot,
 				struct pinctrl_dev *pctldev);
 void pinmux_init_debugfs(struct dentry *subsys_root);
@@ -21,7 +21,7 @@ void pinmux_unhog_maps(struct pinctrl_dev *pctldev);
 
 #else
 
-static inline int pinmux_check_ops(const struct pinmux_ops *ops)
+static inline int pinmux_check_ops(struct pinctrl_dev *pctldev)
 {
 	return 0;
 }