CVE-2026-89445iommufd: Fix UAF in selftest IOPF reporting

Official 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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/fd2e7ac94d6d813548b021473c3dddc30c8c07d1
• https://git.kernel.org/stable/c/cab2895729516799384d48560e6fca105fb3f927
• https://git.kernel.org/stable/c/e27e90bde68b2ab92e63ed19caad1ef57188bea0
• https://git.kernel.org/stable/c/8c07df7cdfcf52f1ff276c588612aabc6c6b8399