iommu/vt-d: Call __dmar_remove_one_dev_info with valid pointer

It is possible for archdata.iommu to be set to
DEFER_DEVICE_DOMAIN_INFO or DUMMY_DEVICE_DOMAIN_INFO so check for
those values before calling __dmar_remove_one_dev_info. Without a
check it can result in a null pointer dereference. This has been seen
while booting a kdump kernel on an HP dl380 gen9.

Cc: Joerg Roedel <[email protected]>
Cc: Lu Baolu <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: [email protected] # 5.3+
Cc: [email protected]
Fixes: ae23bfb ("iommu/vt-d: Detach domain before using a private one")
Signed-off-by: Jerry Snitselaar <[email protected]>
Acked-by: Lu Baolu <[email protected]>
Signed-off-by: Joerg Roedel <[email protected]>

Author: snits

drivers/iommu/intel-iommu.c

@@ -5163,7 +5163,8 @@ static void dmar_remove_one_dev_info(struct device *dev)
 
 	spin_lock_irqsave(&device_domain_lock, flags);
 	info = dev->archdata.iommu;
-	if (info)
+	if (info && info != DEFER_DEVICE_DOMAIN_INFO
+	    && info != DUMMY_DEVICE_DOMAIN_INFO)
 		__dmar_remove_one_dev_info(info);
 	spin_unlock_irqrestore(&device_domain_lock, flags);
 }