CVE-2026-89445

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.