linux-kernel - [PATCH] iommu: Check dev->iommu in iommu_dev

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Date:   Tue, 26 Jan 2021 13:06:29 +0000
From:   Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
To:     <linux-kernel@...r.kernel.org>, <iommu@...ts.linux-foundation.org>
CC:     <joro@...tes.org>, <jean-philippe@...aro.org>, <will@...nel.org>,
        <prime.zeng@...ilicon.com>, <linuxarm@...neuler.org>
Subject: [PATCH] iommu: Check dev->iommu in iommu_dev_xxx functions

The device iommu probe/attach might have failed leaving dev->iommu
to NULL and device drivers may still invoke these functions resulting
a crash in iommu vendor driver code. Hence make sure we check that.

Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
---
 drivers/iommu/iommu.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index ffeebda8d6de..cb68153c5cc0 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2867,7 +2867,7 @@ bool iommu_dev_has_feature(struct device *dev, enum iommu_dev_features feat)
 {
 	const struct iommu_ops *ops = dev->bus->iommu_ops;
 
-	if (ops && ops->dev_has_feat)
+	if (dev->iommu && ops && ops->dev_has_feat)
 		return ops->dev_has_feat(dev, feat);
 
 	return false;
@@ -2878,7 +2878,7 @@ int iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features feat)
 {
 	const struct iommu_ops *ops = dev->bus->iommu_ops;
 
-	if (ops && ops->dev_enable_feat)
+	if (dev->iommu && ops && ops->dev_enable_feat)
 		return ops->dev_enable_feat(dev, feat);
 
 	return -ENODEV;
@@ -2894,7 +2894,7 @@ int iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat)
 {
 	const struct iommu_ops *ops = dev->bus->iommu_ops;
 
-	if (ops && ops->dev_disable_feat)
+	if (dev->iommu && ops && ops->dev_disable_feat)
 		return ops->dev_disable_feat(dev, feat);
 
 	return -EBUSY;
@@ -2905,7 +2905,7 @@ bool iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features feat)
 {
 	const struct iommu_ops *ops = dev->bus->iommu_ops;
 
-	if (ops && ops->dev_feat_enabled)
+	if (dev->iommu && ops && ops->dev_feat_enabled)
 		return ops->dev_feat_enabled(dev, feat);
 
 	return false;
-- 
2.17.1