linux-kernel - [PATCH] iommu/vt-d: call __dmar_remove_one_dev

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Date:   Tue, 21 Jan 2020 17:34:26 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     iommu@...ts.linux-foundation.org
Cc:     Joerg Roedel <joro@...tes.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        David Woodhouse <dwmw2@...radead.org>, stable@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] 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 <joro@...tes.org>
Cc: Lu Baolu <baolu.lu@...ux.intel.com>
Cc: David Woodhouse <dwmw2@...radead.org>
Cc: stable@...r.kernel.org # 5.3+
Cc: linux-kernel@...r.kernel.org
Fixes: ae23bfb68f28 ("iommu/vt-d: Detach domain before using a private one")
Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.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)
 
 	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);
 }
-- 
2.24.0