power: supply: pf1550: 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: 4b6b6433a97d ("power: supply: pf1550: add battery charger support")
Signed-off-by: Waqar Hameed <waqar.hameed@axis.com>
Reviewed-by: Samuel Kayode <samkay014@gmail.com>
Link: https://patch.msgid.link/ae5a71b7e4dd2967d8fdcc531065cc71b17c86f5.1766268280.git.waqar.hameed@axis.com
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

diff --git a/drivers/power/supply/pf1550-charger.c b/drivers/power/supply/pf1550-charger.c
index 98f1ee8eca3bc8dff2c3a697d157b9e3da204fe2..a457862ef4610874308aa975a54915bec30bb663 100644 (file)
--- a/drivers/power/supply/pf1550-charger.c
+++ b/drivers/power/supply/pf1550-charger.c
@@ -584,22 +584,6 @@ static int pf1550_charger_probe(struct platform_device *pdev)
                return dev_err_probe(chg->dev, ret,
                                     "failed to add battery sense work\n");
 
-       for (i = 0; i < PF1550_CHARGER_IRQ_NR; i++) {
-               irq = platform_get_irq(pdev, i);
-               if (irq < 0)
-                       return irq;
-
-               chg->virqs[i] = irq;
-
-               ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
-                                               pf1550_charger_irq_handler,
-                                               IRQF_NO_SUSPEND,
-                                               "pf1550-charger", chg);
-               if (ret)
-                       return dev_err_probe(&pdev->dev, ret,
-                                            "failed irq request\n");
-       }
-
        psy_cfg.drv_data = chg;
 
        chg->charger = devm_power_supply_register(&pdev->dev,
@@ -616,6 +600,22 @@ static int pf1550_charger_probe(struct platform_device *pdev)
                return dev_err_probe(&pdev->dev, PTR_ERR(chg->battery),
                                     "failed: power supply register\n");
 
+       for (i = 0; i < PF1550_CHARGER_IRQ_NR; i++) {
+               irq = platform_get_irq(pdev, i);
+               if (irq < 0)
+                       return irq;
+
+               chg->virqs[i] = irq;
+
+               ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
+                                               pf1550_charger_irq_handler,
+                                               IRQF_NO_SUSPEND,
+                                               "pf1550-charger", chg);
+               if (ret)
+                       return dev_err_probe(&pdev->dev, ret,
+                                            "failed irq request\n");
+       }
+
        pf1550_dt_parse_dev_info(chg);
 
        return pf1550_reg_init(chg);