iommu/vt-d: Fix possible use-after-free of private domain

Multiple devices might share a private domain. One real example
is a pci bridge and all devices behind it. When remove a private
domain, make sure that it has been detached from all devices to
avoid use-after-free case.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Fixes: 942067f1b6b97 ("iommu/vt-d: Identify default domains replaced with private")
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 37259b7f95a7efba0a1fc7ff628f204f989d4641..12d094d08c0a2e982fb712b9310ceadf7213013d 100644 (file)
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4791,7 +4791,8 @@ static void __dmar_remove_one_dev_info(struct device_domain_info *info)
 
        /* free the private domain */
        if (domain->flags & DOMAIN_FLAG_LOSE_CHILDREN &&
-           !(domain->flags & DOMAIN_FLAG_STATIC_IDENTITY))
+           !(domain->flags & DOMAIN_FLAG_STATIC_IDENTITY) &&
+           list_empty(&domain->devices))
                domain_exit(info->domain);
 
        free_devinfo_mem(info);