Commit 5c9ecd8e authored by Gui-Dong Han's avatar Gui-Dong Han Committed by Rafael J. Wysocki
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PM: sleep: wakeirq: harden dev_pm_clear_wake_irq() against races 



dev_pm_clear_wake_irq() currently uses a dangerous pattern where
dev->power.wakeirq is read and checked for NULL outside the lock.
If two callers invoke this function concurrently, both might see
a valid pointer and proceed. This could result in a double-free
when the second caller acquires the lock and tries to release the
same object.

Address this by removing the lockless check of dev->power.wakeirq.
Instead, acquire dev->power.lock immediately to ensure the check and
the subsequent operations are atomic. If dev->power.wakeirq is NULL
under the lock, simply unlock and return. This guarantees that
concurrent calls cannot race to free the same object.

Based on a quick scan of current users, I did not find an actual bug as
drivers seem to rely on their own synchronization. However, since
asynchronous usage patterns exist (e.g., in
drivers/net/wireless/ti/wlcore), I believe a race is theoretically
possible if the API is used less carefully in the future. This change
hardens the API to be robust against such cases.

Fixes: 4990d4fe ("PM / Wakeirq: Add automated device wake IRQ handling")
Signed-off-by: default avatarGui-Dong Han <hanguidong02@gmail.com>
Link: https://patch.msgid.link/20260203031943.1924-1-hanguidong02@gmail.com


Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 75ce02f4

drivers/base/power/wakeirq.c

+6 −3
Original line number Diff line number Diff line
@@ -83,13 +83,16 @@ EXPORT_SYMBOL_GPL(dev_pm_set_wake_irq); 
 */

void dev_pm_clear_wake_irq(struct device *dev)

{

	struct wake_irq *wirq = dev->power.wakeirq;

	struct wake_irq *wirq;

	unsigned long flags;



	if (!wirq)

	spin_lock_irqsave(&dev->power.lock, flags);

	wirq = dev->power.wakeirq;

	if (!wirq) {

		spin_unlock_irqrestore(&dev->power.lock, flags);

		return;

	}



	spin_lock_irqsave(&dev->power.lock, flags);

	device_wakeup_detach_irq(dev);

	dev->power.wakeirq = NULL;

	spin_unlock_irqrestore(&dev->power.lock, flags);