power: supply: ab8500: 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()`.

Commit 1c1f13a006ed ("power: supply: ab8500: Move to componentized
binding") introduced this issue during a refactorization. Fix this racy
use-after-free by making sure the IRQ is requested _after_ the
registration of the `power_supply` handle.

Fixes: 1c1f13a006ed ("power: supply: ab8500: Move to componentized binding")
Signed-off-by: Waqar Hameed <waqar.hameed@axis.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/ccf83a09942cb8dda3dff70b2682f2c2e9cb97f2.1766268280.git.waqar.hameed@axis.com
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

diff --git a/drivers/power/supply/ab8500_charger.c b/drivers/power/supply/ab8500_charger.c
index 5f4537766e5b907d66b44964c320bc31acc7408b..1813fbdfa1c1f62560ef53cd46b62246fc287eb2 100644 (file)
--- a/drivers/power/supply/ab8500_charger.c
+++ b/drivers/power/supply/ab8500_charger.c
@@ -3466,26 +3466,6 @@ static int ab8500_charger_probe(struct platform_device *pdev)
                return ret;
        }
 
-       /* Request interrupts */
-       for (i = 0; i < ARRAY_SIZE(ab8500_charger_irq); i++) {
-               irq = platform_get_irq_byname(pdev, ab8500_charger_irq[i].name);
-               if (irq < 0)
-                       return irq;
-
-               ret = devm_request_threaded_irq(dev,
-                       irq, NULL, ab8500_charger_irq[i].isr,
-                       IRQF_SHARED | IRQF_NO_SUSPEND | IRQF_ONESHOT,
-                       ab8500_charger_irq[i].name, di);
-
-               if (ret != 0) {
-                       dev_err(dev, "failed to request %s IRQ %d: %d\n"
-                               , ab8500_charger_irq[i].name, irq, ret);
-                       return ret;
-               }
-               dev_dbg(dev, "Requested %s IRQ %d: %d\n",
-                       ab8500_charger_irq[i].name, irq, ret);
-       }
-
        /* initialize lock */
        spin_lock_init(&di->usb_state.usb_lock);
        mutex_init(&di->usb_ipt_crnt_lock);
@@ -3614,6 +3594,26 @@ static int ab8500_charger_probe(struct platform_device *pdev)
                return PTR_ERR(di->usb_chg.psy);
        }
 
+       /* Request interrupts */
+       for (i = 0; i < ARRAY_SIZE(ab8500_charger_irq); i++) {
+               irq = platform_get_irq_byname(pdev, ab8500_charger_irq[i].name);
+               if (irq < 0)
+                       return irq;
+
+               ret = devm_request_threaded_irq(dev,
+                       irq, NULL, ab8500_charger_irq[i].isr,
+                       IRQF_SHARED | IRQF_NO_SUSPEND | IRQF_ONESHOT,
+                       ab8500_charger_irq[i].name, di);
+
+               if (ret != 0) {
+                       dev_err(dev, "failed to request %s IRQ %d: %d\n"
+                               , ab8500_charger_irq[i].name, irq, ret);
+                       return ret;
+               }
+               dev_dbg(dev, "Requested %s IRQ %d: %d\n",
+                       ab8500_charger_irq[i].name, irq, ret);
+       }
+
        /*
         * Check what battery we have, since we always have the USB
         * psy, use that as a handle.