CVE-2026-89445

/// Technical description

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

iommufd: Fix UAF in selftest IOPF reporting

IOMMUFD selftest TRIGGER_IOPF borrows an attach handle from

group->pasid_array without synchronizing against PASID detach,

then a concurrent iommu_report_device_fault() can dereference

that borrowed handle's domain pointer after the detach erases

the handle and frees the backing struct iommufd_attach_handle.

TRIGGER_IOPF then dereferences the freed handle, causing a UAF.

Fix by adding a iopf_rwsem in mock_dev to follow the expected design

of a real driver. Hold its read side across the whole

iommu_report_device_fault() call, and its write side around every

path that attaches, detaches, or replaces a device domain.

This can block new reports and drains in-flight reports before an old

attach handle or the IOPF fault parameter can be removed.

Also take the write side while registering a mock device, since

it can invoke the mock driver's default-domain attach callback.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References