PCI: Prevent sysfs disable of device while driver is attached

Manipulating the enable_cnt behind the back of the driver will wreak complete havoc with the kernel state, so disallow it. Signed-off-by: Christoph Hellwig <[email protected]> Signed-off-by: Bjorn Helgaas <[email protected]> Reviewed-by: Johannes Thumshirn <[email protected]> Acked-by: Keith Busch <[email protected]>
jix · May 25, 2018 · 6f5cdfa · 6f5cdfa
1 parent 17e8f0d
commit 6f5cdfa
Showing 1 changed file with 9 additions and 6 deletions.
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
@@ -288,13 +288,16 @@ static ssize_t enable_store(struct device *dev, struct device_attribute *attr,
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
-	if (!val) {
-		if (pci_is_enabled(pdev))
-			pci_disable_device(pdev);
-		else
-			result = -EIO;
-	} else
+	device_lock(dev);
+	if (dev->driver)
+		result = -EBUSY;
+	else if (val)
 		result = pci_enable_device(pdev);
+	else if (pci_is_enabled(pdev))
+		pci_disable_device(pdev);
+	else
+		result = -EIO;
+	device_unlock(dev);
 
 	return result < 0 ? result : count;
 }