iommu: Return right value in iommu_sva_bind_device()

CVE-2024-40945

What is CVE-2024-40945?

In the Linux kernel, the following vulnerability has been resolved:

iommu: Return right value in iommu_sva_bind_device()

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.

References