pinctrl: axp209: Fix NULL pointer dereference after allocation

There is no check that allocation in axp20x_funcs_groups_from_mask
is successful.
The patch adds corresponding check and return values.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Anton Vasilyev <vasilyev@ispras.ru>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-axp209.c

@@ -316,7 +316,7 @@ static const struct pinctrl_ops axp20x_pctrl_ops = {
 	.get_group_pins		= axp20x_group_pins,
 };
 
-static void axp20x_funcs_groups_from_mask(struct device *dev, unsigned int mask,
+static int axp20x_funcs_groups_from_mask(struct device *dev, unsigned int mask,
 					  unsigned int mask_len,
 					  struct axp20x_pinctrl_function *func,
 					  const struct pinctrl_pin_desc *pins)
@@ -331,18 +331,22 @@ static void axp20x_funcs_groups_from_mask(struct device *dev, unsigned int mask,
 		func->groups = devm_kcalloc(dev,
 					    ngroups, sizeof(const char *),
 					    GFP_KERNEL);
+		if (!func->groups)
+			return -ENOMEM;
 		group = func->groups;
 		for_each_set_bit(bit, &mask_cpy, mask_len) {
 			*group = pins[bit].name;
 			group++;
 		}
 	}
+
+	return 0;
 }
 
-static void axp20x_build_funcs_groups(struct platform_device *pdev)
+static int axp20x_build_funcs_groups(struct platform_device *pdev)
 {
 	struct axp20x_pctl *pctl = platform_get_drvdata(pdev);
-	int i, pin, npins = pctl->desc->npins;
+	int i, ret, pin, npins = pctl->desc->npins;
 
 	pctl->funcs[AXP20X_FUNC_GPIO_OUT].name = "gpio_out";
 	pctl->funcs[AXP20X_FUNC_GPIO_OUT].muxval = AXP20X_MUX_GPIO_OUT;
@@ -366,13 +370,19 @@ static void axp20x_build_funcs_groups(struct platform_device *pdev)
 			pctl->funcs[i].groups[pin] = pctl->desc->pins[pin].name;
 	}
 
-	axp20x_funcs_groups_from_mask(&pdev->dev, pctl->desc->ldo_mask,
+	ret = axp20x_funcs_groups_from_mask(&pdev->dev, pctl->desc->ldo_mask,
 				      npins, &pctl->funcs[AXP20X_FUNC_LDO],
 				      pctl->desc->pins);
+	if (ret)
+		return ret;
 
-	axp20x_funcs_groups_from_mask(&pdev->dev, pctl->desc->adc_mask,
+	ret = axp20x_funcs_groups_from_mask(&pdev->dev, pctl->desc->adc_mask,
 				      npins, &pctl->funcs[AXP20X_FUNC_ADC],
 				      pctl->desc->pins);
+	if (ret)
+		return ret;
+
+	return 0;
 }
 
 static const struct of_device_id axp20x_pctl_match[] = {
@@ -424,7 +434,11 @@ static int axp20x_pctl_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, pctl);
 
-	axp20x_build_funcs_groups(pdev);
+	ret = axp20x_build_funcs_groups(pdev);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to build groups\n");
+		return ret;
+	}
 
 	pctrl_desc = devm_kzalloc(&pdev->dev, sizeof(*pctrl_desc), GFP_KERNEL);
 	if (!pctrl_desc)