CVE-2026-80894iommufd: Fix wrong hwpt passed to iommufd_auto_response_faults on replace

Official description

In the Linux kernel, the following vulnerability has been resolved: iommufd: Fix wrong hwpt passed to iommufd_auto_response_faults on replace iommufd_hwpt_replace_device() calls: iommufd_auto_response_faults(hwpt, old_handle); passing the *new* hwpt together with the handle of the device's *old* domain. This should be a parameter mismatch: 1. Semantically, iommufd_auto_response_faults(x, handle) scans x->fault's deliver list and response xarray for groups matching "handle". A group is queued under the hwpt that was attached at fault-delivery time. old_handle is fetched *before* the domain switch, so its group lives on old->fault, not on the new hwpt->fault. 2. Historically, the first argument was "old". The routine was introduced by commit b7d8833677ba ("iommufd: Fault-capable hwpt attach/detach/replace") as __fault_domain_replace_dev() in fault.c, correctly calling iommufd_auto_response_faults(old, curr). Commit fb21b1568ada ("iommufd: Make attach_handle generic than fault specific") moved this into iommufd_hwpt_replace_device() in device.c and swapped it to "hwpt". This should be a refactor regression, not an intentional change. Fix this by passing "old" instead.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/adb87155b67f9759ff010c0a99559f5bffa45dcf
• https://git.kernel.org/stable/c/564ac339c0f8bada4e77a57a92bab9d3df635e07
• https://git.kernel.org/stable/c/8eb077025279304268bd58657f0af3d388822b21
• https://git.kernel.org/stable/c/ba5c0f28a26e7d9be1e0997f8920dd638e2782fd