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

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 <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
nmenon · Jan 14, 2020 · b743512 · b743512
1 parent fa4e7fc
commit b743512
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/drivers/uio/uio_dmem_genirq.c b/drivers/uio/uio_dmem_genirq.c
@@ -132,11 +132,13 @@ 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;
 }