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From:   Jerry Snitselaar <jsnitsel@redhat.com>
To:     iommu@lists.linux-foundation.org
Cc:     Joerg Roedel <joro@8bytes.org>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        David Woodhouse <dwmw2@infradead.org>, stable@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] iommu/vt-d: call __dmar_remove_one_dev_info with valid pointer
Date:   Tue, 21 Jan 2020 17:34:26 -0700
Message-Id: <20200122003426.16079-1-jsnitsel@redhat.com>
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Sender: linux-kernel-owner@vger.kernel.org
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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 <joro@8bytes.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: stable@vger.kernel.org # 5.3+
Cc: linux-kernel@vger.kernel.org
Fixes: ae23bfb68f28 ("iommu/vt-d: Detach domain before using a private on=
e")
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.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 1801f0aaf013..932267f49f9a 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5163,7 +5163,8 @@ static void dmar_remove_one_dev_info(struct device =
*dev)
=20
 	spin_lock_irqsave(&device_domain_lock, flags);
 	info =3D dev->archdata.iommu;
-	if (info)
+	if (info && info !=3D DEFER_DEVICE_DOMAIN_INFO
+	    && info !=3D DUMMY_DEVICE_DOMAIN_INFO)
 		__dmar_remove_one_dev_info(info);
 	spin_unlock_irqrestore(&device_domain_lock, flags);
 }
--=20
2.24.0