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power: supply: sbs-battery: 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. Keep the old behavior of
just printing a warning in case of any failures during the IRQ request
and finishing the probe successfully.

Fixes: d2cec82c28 ("power: sbs-battery: Request threaded irq and fix dev callback cookie")
Signed-off-by: Waqar Hameed <waqar.hameed@axis.com>
Reviewed-by: Phil Reid <preid@electromag.com.au>
Link: https://patch.msgid.link/0ef896e002495e615157b482d18a437af19ddcd0.1766268280.git.waqar.hameed@axis.com
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
This commit is contained in:
Waqar Hameed 2025-12-20 23:36:02 +01:00 • committed by Sebastian Reichel
parent e2febe375e
commit 8d59cf3887
1 changed files with 18 additions and 18 deletions
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36
drivers/power/supply/sbs-battery.c
View file

@ -1174,24 +1174,6 @@ static int sbs_probe(struct i2c_client *client)
i2c_set_clientdata(client, chip);
if (!chip->gpio_detect)
goto skip_gpio;
irq = gpiod_to_irq(chip->gpio_detect);
if (irq <= 0) {
dev_warn(&client->dev, "Failed to get gpio as irq: %d\n", irq);
goto skip_gpio;
}
rc = devm_request_threaded_irq(&client->dev, irq, NULL, sbs_irq,
IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
dev_name(&client->dev), chip);
if (rc) {
dev_warn(&client->dev, "Failed to request irq: %d\n", rc);
goto skip_gpio;
}
skip_gpio:
/*
* Before we register, we might need to make sure we can actually talk
* to the battery.
@ -1217,6 +1199,24 @@ skip_gpio:
return dev_err_probe(&client->dev, PTR_ERR(chip->power_supply),
"Failed to register power supply\n");
if (!chip->gpio_detect)
goto out;
irq = gpiod_to_irq(chip->gpio_detect);
if (irq <= 0) {
dev_warn(&client->dev, "Failed to get gpio as irq: %d\n", irq);
goto out;
}
rc = devm_request_threaded_irq(&client->dev, irq, NULL, sbs_irq,
IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
dev_name(&client->dev), chip);
if (rc) {
dev_warn(&client->dev, "Failed to request irq: %d\n", rc);
goto out;
}
out:
dev_info(&client->dev,
"%s: battery gas gauge device registered\n", client->name);