linux-kernel - [PATCH 08/11] power: supply: pm8916_bms_vm: Fix use-after-free in power_supply

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Message-ID: <2749c09ff81fcac87ae48147e216135450d8c067.1766268280.git.waqar.hameed@axis.com>
Date: Sat, 20 Dec 2025 23:36:01 +0100
From: Waqar Hameed <waqar.hameed@...s.com>
To: Sebastian Reichel <sre@...nel.org>, Nikita Travkin <nikita@...n.ru>
CC: <kernel@...s.com>, <linux-pm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH 08/11] power: supply: pm8916_bms_vm: Fix use-after-free in
 power_supply_changed()

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: 098bce1838e0 ("power: supply: Add pm8916 VM-BMS support")
Signed-off-by: Waqar Hameed <waqar.hameed@...s.com>
---
 drivers/power/supply/pm8916_bms_vm.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/power/supply/pm8916_bms_vm.c b/drivers/power/supply/pm8916_bms_vm.c
index 5120be086e6ff..de5d571c03e21 100644
--- a/drivers/power/supply/pm8916_bms_vm.c
+++ b/drivers/power/supply/pm8916_bms_vm.c
@@ -167,15 +167,6 @@ static int pm8916_bms_vm_battery_probe(struct platform_device *pdev)
 	if (ret < 0)
 		return -EINVAL;

-	irq = platform_get_irq_byname(pdev, "fifo");
-	if (irq < 0)
-		return irq;
-
-	ret = devm_request_threaded_irq(dev, irq, NULL, pm8916_bms_vm_fifo_update_done_irq,
-					IRQF_ONESHOT, "pm8916_vm_bms", bat);
-	if (ret)
-		return ret;
-
 	ret = regmap_bulk_read(bat->regmap, bat->reg + PM8916_PERPH_TYPE, &tmp, 2);
 	if (ret)
 		goto comm_error;
@@ -220,6 +211,15 @@ static int pm8916_bms_vm_battery_probe(struct platform_device *pdev)
 	if (ret)
 		return dev_err_probe(dev, ret, "Unable to get battery info\n");

+	irq = platform_get_irq_byname(pdev, "fifo");
+	if (irq < 0)
+		return irq;
+
+	ret = devm_request_threaded_irq(dev, irq, NULL, pm8916_bms_vm_fifo_update_done_irq,
+					IRQF_ONESHOT, "pm8916_vm_bms", bat);
+	if (ret)
+		return ret;
+
 	platform_set_drvdata(pdev, bat);

 	return 0;
-- 
2.39.5