[PATCH 5.15 094/356] iommu: Return right value in iommu_sva_bind_device()

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5.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

[ Upstream commit 89e8a2366e3bce584b6c01549d5019c5cda1205e ]

iommu_sva_bind_device() should return either a sva bond handle or an
ERR_PTR value in error cases. Existing drivers (idxd and uacce) only
check the return value with IS_ERR(). This could potentially lead to
a kernel NULL pointer dereference issue if the function returns NULL
instead of an error pointer.

In reality, this doesn't cause any problems because iommu_sva_bind_device()
only returns NULL when the kernel is not configured with CONFIG_IOMMU_SVA.
In this case, iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) will
return an error, and the device drivers won't call iommu_sva_bind_device()
at all.

Fixes: 26b25a2b98e4 ("iommu: Bind process address spaces to devices")
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Vasant Hegde <vasant.hegde@xxxxxxx>
Link: https://lore.kernel.org/r/20240528042528.71396-1-baolu.lu@xxxxxxxxxxxxxxx
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 include/linux/iommu.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index d2f3435e7d176..2202a665b0927 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -1038,7 +1038,7 @@ iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev)
 static inline struct iommu_sva *
 iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
 {
-	return NULL;
+	return ERR_PTR(-ENODEV);
 }
 
 static inline void iommu_sva_unbind_device(struct iommu_sva *handle)
-- 
2.43.0







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