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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Joerg Roedel <jroedel@suse.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.11 401/601] iommu: Check dev->iommu in iommu_dev_xxx functions
Date:   Wed, 12 May 2021 16:47:58 +0200
Message-Id: <20210512144841.015967162@linuxfoundation.org>
In-Reply-To: <20210512144827.811958675@linuxfoundation.org>
References: <20210512144827.811958675@linuxfoundation.org>
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From: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>

[ Upstream commit b9abb19fa5fd2d8a4be61c6cd4b2a48aa1a17f9c ]

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

Hence make sure we check that.

Fixes: a3a195929d40 ("iommu: Add APIs for multiple domains per device")
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20210303173611.520-1-shameerali.kolothum.thodi@huawei.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/iommu/iommu.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index fd5f59373fc6..0e0140454de8 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2889,10 +2889,12 @@ EXPORT_SYMBOL_GPL(iommu_dev_has_feature);
 
 int iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features feat)
 {
-	const struct iommu_ops *ops = dev->bus->iommu_ops;
+	if (dev->iommu && dev->iommu->iommu_dev) {
+		const struct iommu_ops *ops = dev->iommu->iommu_dev->ops;
 
-	if (ops && ops->dev_enable_feat)
-		return ops->dev_enable_feat(dev, feat);
+		if (ops->dev_enable_feat)
+			return ops->dev_enable_feat(dev, feat);
+	}
 
 	return -ENODEV;
 }
@@ -2905,10 +2907,12 @@ EXPORT_SYMBOL_GPL(iommu_dev_enable_feature);
  */
 int iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat)
 {
-	const struct iommu_ops *ops = dev->bus->iommu_ops;
+	if (dev->iommu && dev->iommu->iommu_dev) {
+		const struct iommu_ops *ops = dev->iommu->iommu_dev->ops;
 
-	if (ops && ops->dev_disable_feat)
-		return ops->dev_disable_feat(dev, feat);
+		if (ops->dev_disable_feat)
+			return ops->dev_disable_feat(dev, feat);
+	}
 
 	return -EBUSY;
 }
@@ -2916,10 +2920,12 @@ EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);
 
 bool iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features feat)
 {
-	const struct iommu_ops *ops = dev->bus->iommu_ops;
+	if (dev->iommu && dev->iommu->iommu_dev) {
+		const struct iommu_ops *ops = dev->iommu->iommu_dev->ops;
 
-	if (ops && ops->dev_feat_enabled)
-		return ops->dev_feat_enabled(dev, feat);
+		if (ops->dev_feat_enabled)
+			return ops->dev_feat_enabled(dev, feat);
+	}
 
 	return false;
 }
-- 
2.30.2