linux-kernel - [PATCH 2/2] iommu/vt-d: Fix possible use-after-free of private domain

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Date:   Tue,  6 Aug 2019 08:14:09 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>
Cc:     ashok.raj@...el.com, jacob.jun.pan@...el.com, kevin.tian@...el.com,
        Alex Williamson <alex.williamson@...hat.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: [PATCH 2/2] 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@...el.com>
Cc: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc: Kevin Tian <kevin.tian@...el.com>
Cc: Alex Williamson <alex.williamson@...hat.com>
Fixes: 942067f1b6b97 ("iommu/vt-d: Identify default domains replaced with private")
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel-iommu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 37259b7f95a7..12d094d08c0a 100644
--- 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);
-- 
2.17.1