[PATCH AUTOSEL 4.14 07/13] hwmon: (aspeed-pwm-tacho) Avoid possible buffer overflow

[Sasha Levin <sashal@kernel.org>]

From: Evgeny Novikov <novikov@ispras.ru>

[ Upstream commit bc4071aafcf4d0535ee423b69167696d6c03207d ]

aspeed_create_fan() reads a pwm_port value using of_property_read_u32().
If pwm_port will be more than ARRAY_SIZE(pwm_port_params), there will be
a buffer overflow in
aspeed_create_pwm_port()->aspeed_set_pwm_port_enable(). The patch fixes
the potential buffer overflow.

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

Signed-off-by: Evgeny Novikov <novikov@ispras.ru>
Link: https://lore.kernel.org/r/20200703111518.9644-1-novikov@ispras.ru
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hwmon/aspeed-pwm-tacho.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/hwmon/aspeed-pwm-tacho.c b/drivers/hwmon/aspeed-pwm-tacho.c
index 69b97d45e3cbb..e4337e9dda444 100644
--- a/drivers/hwmon/aspeed-pwm-tacho.c
+++ b/drivers/hwmon/aspeed-pwm-tacho.c
@@ -878,6 +878,8 @@ static int aspeed_create_fan(struct device *dev,
 	ret = of_property_read_u32(child, "reg", &pwm_port);
 	if (ret)
 		return ret;
+	if (pwm_port >= ARRAY_SIZE(pwm_port_params))
+		return -EINVAL;
 	aspeed_create_pwm_port(priv, (u8)pwm_port);
 
 	ret = of_property_count_u8_elems(child, "cooling-levels");
-- 
2.25.1