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power: supply: goldfish: Fix use-after-free in power_supply_changed()

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Using the `devm_` variant for requesting IRQ _before_ the `devm_`
variant for allocating/registering the `power_supply` handle, means that
the `power_supply` handle will be deallocated/unregistered _before_ the
interrupt handler (since `devm_` naturally deallocates in reverse
allocation order). This means that during removal, there is a race
condition where an interrupt can fire just _after_ the `power_supply`
handle has been freed, *but* just _before_ the corresponding
unregistration of the IRQ handler has run.

This will lead to the IRQ handler calling `power_supply_changed()` with
a freed `power_supply` handle. Which usually crashes the system or
otherwise silently corrupts the memory...

Note that there is a similar situation which can also happen during
`probe()`; the possibility of an interrupt firing _before_ registering
the `power_supply` handle. This would then lead to the nasty situation
of using the `power_supply` handle *uninitialized* in
`power_supply_changed()`.

Fix this racy use-after-free by making sure the IRQ is requested _after_
the registration of the `power_supply` handle.

Fixes: 84d7b76874 ("power: Add battery driver for goldfish emulator")
Signed-off-by: Waqar Hameed <waqar.hameed@axis.com>
Link: https://patch.msgid.link/500a606bb6fb6f2bb8d797e19a00cea9dd7b03c1.1766268280.git.waqar.hameed@axis.com
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
This commit is contained in:
Waqar Hameed
2025-12-20 23:36:00 +01:00
committed by Sebastian Reichel
parent 642f33e34b
commit b2ce982e2e
1 changed files with 6 additions and 6 deletions
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12
drivers/power/supply/goldfish_battery.c
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@@ -224,12 +224,6 @@ static int goldfish_battery_probe(struct platform_device *pdev)
if (data->irq < 0)
return -ENODEV;
ret = devm_request_irq(&pdev->dev, data->irq,
goldfish_battery_interrupt,
IRQF_SHARED, pdev->name, data);
if (ret)
return ret;
psy_cfg.drv_data = data;
data->ac = devm_power_supply_register(&pdev->dev,
@@ -244,6 +238,12 @@ static int goldfish_battery_probe(struct platform_device *pdev)
if (IS_ERR(data->battery))
return PTR_ERR(data->battery);
ret = devm_request_irq(&pdev->dev, data->irq,
goldfish_battery_interrupt,
IRQF_SHARED, pdev->name, data);
if (ret)
return ret;
GOLDFISH_BATTERY_WRITE(data, BATTERY_INT_ENABLE, BATTERY_INT_MASK);
return 0;
}