iommu: Return right value in iommu_sva_bind_device()

commit 89e8a2366e3bce584b6c01549d5019c5cda1205e upstream.

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@linux.intel.com>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20240528042528.71396-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Bin Lan <lanbincn@qq.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 9d87090953bcc737e9bf514977c5d5d96dc7df3f..2bfa9611be67215e8145b43db2cc5a917e434466 100644 (file)
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -999,7 +999,7 @@ iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat)
 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)