From 8d59cf3887fbabacef53bfba473e33e8a8d9d07b Mon Sep 17 00:00:00 2001 From: Waqar Hameed Date: Sat, 20 Dec 2025 23:36:02 +0100 Subject: [PATCH] power: supply: sbs-battery: 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. Keep the old behavior of just printing a warning in case of any failures during the IRQ request and finishing the probe successfully. Fixes: d2cec82c2880 ("power: sbs-battery: Request threaded irq and fix dev callback cookie") Signed-off-by: Waqar Hameed Reviewed-by: Phil Reid Link: https://patch.msgid.link/0ef896e002495e615157b482d18a437af19ddcd0.1766268280.git.waqar.hameed@axis.com Signed-off-by: Sebastian Reichel --- drivers/power/supply/sbs-battery.c | 36 +++++++++++++++--------------- 1 file changed, 18 insertions(+), 18 deletions(-) diff --git a/drivers/power/supply/sbs-battery.c b/drivers/power/supply/sbs-battery.c index 943c82ee978f4..43c48196c1674 100644 --- a/drivers/power/supply/sbs-battery.c +++ b/drivers/power/supply/sbs-battery.c @@ -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); -- 2.47.3