[PATCH 5.10 072/120] iommu: Check dev->iommu in dev_iommu_priv_get() before dereferencing it

[Greg Kroah-Hartman]

From: Joerg Roedel <jroedel@xxxxxxx>

commit 4c9fb5d9140802db4db9f66c23887f43174e113c upstream.

The dev_iommu_priv_get() needs a similar check to
dev_iommu_fwspec_get() to make sure no NULL-ptr is dereferenced.

Fixes: 05a0542b456e1 ("iommu/amd: Store dev_data as device iommu private data")
Cc: stable@xxxxxxxxxxxxxxx	# v5.8+
Link: https://lore.kernel.org/r/20210202145419.29143-1-joro@xxxxxxxxxx
Reference: https://bugzilla.kernel.org/show_bug.cgi?id=211241
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 include/linux/iommu.h |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -614,7 +614,10 @@ static inline void dev_iommu_fwspec_set(
 
 static inline void *dev_iommu_priv_get(struct device *dev)
 {
-	return dev->iommu->priv;
+	if (dev->iommu)
+		return dev->iommu->priv;
+	else
+		return NULL;
 }
 
 static inline void dev_iommu_priv_set(struct device *dev, void *priv)