regulator: max77802: Bounds check regulator id against opmode

Explicitly bounds-check the id before accessing the opmode array. Seen
with GCC 13:

../drivers/regulator/max77802-regulator.c: In function 'max77802_enable':
../drivers/regulator/max77802-regulator.c:217:29: warning: array subscript [0, 41] is outside array bounds of 'unsigned int[42]' [-Warray-bounds=]
  217 |         if (max77802->opmode[id] == MAX77802_OFF_PWRREQ)
      |             ~~~~~~~~~~~~~~~~^~~~
../drivers/regulator/max77802-regulator.c:62:22: note: while referencing 'opmode'
   62 |         unsigned int opmode[MAX77802_REG_MAX];
      |                      ^~~~~~

Cc: Javier Martinez Canillas <javier@dowhile0.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20230127225203.never.864-kees@kernel.orgSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/max77802-regulator.c

@@ -94,9 +94,11 @@ static int max77802_set_suspend_disable(struct regulator_dev *rdev)
 {
 	unsigned int val = MAX77802_OFF_PWRREQ;
 	struct max77802_regulator_prv *max77802 = rdev_get_drvdata(rdev);
-	int id = rdev_get_id(rdev);
+	unsigned int id = rdev_get_id(rdev);
 	int shift = max77802_get_opmode_shift(id);
 
+	if (WARN_ON_ONCE(id >= ARRAY_SIZE(max77802->opmode)))
+		return -EINVAL;
 	max77802->opmode[id] = val;
 	return regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
 				  rdev->desc->enable_mask, val << shift);
@@ -110,7 +112,7 @@ static int max77802_set_suspend_disable(struct regulator_dev *rdev)
 static int max77802_set_mode(struct regulator_dev *rdev, unsigned int mode)
 {
 	struct max77802_regulator_prv *max77802 = rdev_get_drvdata(rdev);
-	int id = rdev_get_id(rdev);
+	unsigned int id = rdev_get_id(rdev);
 	unsigned int val;
 	int shift = max77802_get_opmode_shift(id);
 
@@ -127,6 +129,9 @@ static int max77802_set_mode(struct regulator_dev *rdev, unsigned int mode)
 		return -EINVAL;
 	}
 
+	if (WARN_ON_ONCE(id >= ARRAY_SIZE(max77802->opmode)))
+		return -EINVAL;
+
 	max77802->opmode[id] = val;
 	return regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
 				  rdev->desc->enable_mask, val << shift);
@@ -135,8 +140,10 @@ static int max77802_set_mode(struct regulator_dev *rdev, unsigned int mode)
 static unsigned max77802_get_mode(struct regulator_dev *rdev)
 {
 	struct max77802_regulator_prv *max77802 = rdev_get_drvdata(rdev);
-	int id = rdev_get_id(rdev);
+	unsigned int id = rdev_get_id(rdev);
 
+	if (WARN_ON_ONCE(id >= ARRAY_SIZE(max77802->opmode)))
+		return -EINVAL;
 	return max77802_map_mode(max77802->opmode[id]);
 }
 
@@ -160,10 +167,13 @@ static int max77802_set_suspend_mode(struct regulator_dev *rdev,
 				     unsigned int mode)
 {
 	struct max77802_regulator_prv *max77802 = rdev_get_drvdata(rdev);
-	int id = rdev_get_id(rdev);
+	unsigned int id = rdev_get_id(rdev);
 	unsigned int val;
 	int shift = max77802_get_opmode_shift(id);
 
+	if (WARN_ON_ONCE(id >= ARRAY_SIZE(max77802->opmode)))
+		return -EINVAL;
+
 	/*
 	 * If the regulator has been disabled for suspend
 	 * then is invalid to try setting a suspend mode.
@@ -209,9 +219,11 @@ static int max77802_set_suspend_mode(struct regulator_dev *rdev,
 static int max77802_enable(struct regulator_dev *rdev)
 {
 	struct max77802_regulator_prv *max77802 = rdev_get_drvdata(rdev);
-	int id = rdev_get_id(rdev);
+	unsigned int id = rdev_get_id(rdev);
 	int shift = max77802_get_opmode_shift(id);
 
+	if (WARN_ON_ONCE(id >= ARRAY_SIZE(max77802->opmode)))
+		return -EINVAL;
 	if (max77802->opmode[id] == MAX77802_OFF_PWRREQ)
 		max77802->opmode[id] = MAX77802_OPMODE_NORMAL;
 
@@ -495,7 +507,7 @@ static int max77802_pmic_probe(struct platform_device *pdev)
 
 	for (i = 0; i < MAX77802_REG_MAX; i++) {
 		struct regulator_dev *rdev;
-		int id = regulators[i].id;
+		unsigned int id = regulators[i].id;
 		int shift = max77802_get_opmode_shift(id);
 		int ret;
 
@@ -513,10 +525,12 @@ static int max77802_pmic_probe(struct platform_device *pdev)
 		 * the hardware reports OFF as the regulator operating mode.
 		 * Default to operating mode NORMAL in that case.
 		 */
+		if (id < ARRAY_SIZE(max77802->opmode)) {
 			if (val == MAX77802_STATUS_OFF)
 				max77802->opmode[id] = MAX77802_OPMODE_NORMAL;
 			else
 				max77802->opmode[id] = val;
+		}
 
 		rdev = devm_regulator_register(&pdev->dev,
 					       &regulators[i], &config);