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power: supply: cpcap-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.

Fixes: 874b2adbed ("power: supply: cpcap-battery: Add a battery driver")
Signed-off-by: Waqar Hameed <waqar.hameed@axis.com>
Link: https://patch.msgid.link/81db58d610c9a51a68184f856cd431a934cccee2.1766268280.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 5f0b1cb419
commit 642f33e34b
1 changed files with 4 additions and 4 deletions
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8
drivers/power/supply/cpcap-battery.c
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@ -1122,10 +1122,6 @@ static int cpcap_battery_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, ddata);
error = cpcap_battery_init_interrupts(pdev, ddata);
if (error)
return error;
error = cpcap_battery_init_iio(ddata);
if (error)
return error;
@ -1142,6 +1138,10 @@ static int cpcap_battery_probe(struct platform_device *pdev)
return error;
}
error = cpcap_battery_init_interrupts(pdev, ddata);
if (error)
return error;
atomic_set(&ddata->active, 1);
error = cpcap_battery_calibrate(ddata);