[PATCH AUTOSEL 5.4 058/330] mt76: do not use devm API for led classdev

Sasha Levin
2020-09-18T03:11:48Z

From: Felix Fietkau <nbd@nbd.name>

[ Upstream commit 36f7e2b2bb1de86f0072cd49ca93d82b9e8fd894 ]

With the devm API, the unregister happens after the device cleanup is done,
after which the struct mt76_dev which contains the led_cdev has already been
freed. This leads to a use-after-free bug that can crash the system.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wireless/mediatek/mt76/mac80211.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mac80211.c b/drivers/net/wireless/mediatek/mt76/mac80211.c
index 1a2c143b34d01..7be5806a1c398 100644
--- a/drivers/net/wireless/mediatek/mt76/mac80211.c
+++ b/drivers/net/wireless/mediatek/mt76/mac80211.c
@@ -105,7 +105,15 @@ static int mt76_led_init(struct mt76_dev *dev)
dev->led_al = of_property_read_bool(np, "led-active-low");
}

- return devm_led_classdev_register(dev->dev, &dev->led_cdev);
+ return led_classdev_register(dev->dev, &dev->led_cdev);
+}
+
+static void mt76_led_cleanup(struct mt76_dev *dev)
+{
+ if (!dev->led_cdev.brightness_set && !dev->led_cdev.blink_set)
+ return;
+
+ led_classdev_unregister(&dev->led_cdev);
}

static void mt76_init_stream_cap(struct mt76_dev *dev,
@@ -360,6 +368,7 @@ void mt76_unregister_device(struct mt76_dev *dev)
{
struct ieee80211_hw *hw = dev->hw;

+ mt76_led_cleanup(dev);
mt76_tx_status_check(dev, NULL, true);
ieee80211_unregister_hw(hw);
}
--
2.25.1