Commit 0151b03f authored Dec 18, 2019 by Jia-Ju Bai Committed by Greg Kroah-Hartman Feb 28, 2020

uio: fix a sleep-in-atomic-context bug in uio_dmem_genirq_irqcontrol()



[ Upstream commit b74351287d4bd90636c3f48bc188c2f53824c2d4 ]

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

kernel/irq/manage.c, 523:
	synchronize_irq in disable_irq
drivers/uio/uio_dmem_genirq.c, 140:
	disable_irq in uio_dmem_genirq_irqcontrol
drivers/uio/uio_dmem_genirq.c, 134:
	_raw_spin_lock_irqsave in uio_dmem_genirq_irqcontrol

synchronize_irq() can sleep at runtime.

To fix this bug, disable_irq() is called without holding the spinlock.

This bug is 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/20191218094405.6009-1-baijiaju1990@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 5645615a

drivers/uio/uio_dmem_genirq.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -135,11 +135,13 @@ static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
		if (irq_on) {
		if (test_and_clear_bit(0, &priv->flags))
		enable_irq(dev_info->irq);
		spin_unlock_irqrestore(&priv->lock, flags);
		} else {
		if (!test_and_set_bit(0, &priv->flags))
		if (!test_and_set_bit(0, &priv->flags)) {
		spin_unlock_irqrestore(&priv->lock, flags);
		disable_irq(dev_info->irq);
		}
		spin_unlock_irqrestore(&priv->lock, flags);
		}

		return 0;
		}