Commit 442b50c0 authored Dec 18, 2019 by Jia-Ju Bai Committed by Greg Kroah-Hartman Feb 24, 2020

gpio: gpio-grgpio: fix possible sleep-in-atomic-context bugs in grgpio_irq_map/unmap()



[ Upstream commit e36eaf94be8f7bc4e686246eed3cf92d845e2ef8 ]

The driver may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:

drivers/gpio/gpio-grgpio.c, 261:
	request_irq in grgpio_irq_map
drivers/gpio/gpio-grgpio.c, 255:
	_raw_spin_lock_irqsave in grgpio_irq_map

drivers/gpio/gpio-grgpio.c, 318:
	free_irq in grgpio_irq_unmap
drivers/gpio/gpio-grgpio.c, 299:
	_raw_spin_lock_irqsave in grgpio_irq_unmap

request_irq() and free_irq() can sleep at runtime.

To fix these bugs, request_irq() and free_irq() are called without
holding the spinlock.

These bugs are found by a static analysis tool STCheck written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Link: https://lore.kernel.org/r/20191218132605.10594-1-baijiaju1990@gmail.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 67f7f0c7

drivers/gpio/gpio-grgpio.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -258,17 +258,16 @@ static int grgpio_irq_map(struct irq_domain *d, unsigned int irq,
		lirq->irq = irq;
		uirq = &priv->uirqs[lirq->index];
		if (uirq->refcnt == 0) {
		spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);
		ret = request_irq(uirq->uirq, grgpio_irq_handler, 0,
		dev_name(priv->dev), priv);
		if (ret) {
		dev_err(priv->dev,
		"Could not request underlying irq %d\n",
		uirq->uirq);

		spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);

		return ret;
		}
		spin_lock_irqsave(&priv->gc.bgpio_lock, flags);
		}
		uirq->refcnt++;

		@@ -314,8 +313,11 @@ static void grgpio_irq_unmap(struct irq_domain *d, unsigned int irq)
		if (index >= 0) {
		uirq = &priv->uirqs[lirq->index];
		uirq->refcnt--;
		if (uirq->refcnt == 0)
		if (uirq->refcnt == 0) {
		spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);
		free_irq(uirq->uirq, priv);
		return;
		}
		}

		spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);