Re: [PATCH v3 1/2] iommu/iommufd: Fix IOPF group ownership UAF

[Jason Gunthorpe]

On Mon, Jul 20, 2026 at 04:50:16PM +0800, Peiyang He wrote:
> iopf_group_alloc() links each last-page IOPF group into the generic IOPF
> pending list before invoking the domain fault handler.
> iommufd_fault_iopf_handler() also queued an accepted group in the
> IOMMUFD deliver list without removing it from the generic pending list.
> 
> When detach or HWPT replacement drops the device's IOPF reference count
> to zero, an IOMMU driver may call iopf_queue_remove_device(). That
> function responds to and frees groups through the generic pending list
> without removing the same groups from IOMMUFD's deliver list or response
> xarray. A later read, response, or cleanup can then access the freed
> group and cause a UAF.
> 
> Fix this by dequeuing an accepted group from the generic pending list
> before IOMMUFD queues it for userspace response.
> Make iopf_group_response() send a response regardless of pending-list
> membership, so the dequeued group can still be completed by IOMMUFD.
> 
> Closes: https://lore.kernel.org/all/B4F28798E2E784CA+d29f723c-b2b5-4b67-8d1c-4f7b9b0b27cb@xxxxxxxxxxxxxxxx/
> Fixes: 34765cbc679c ("iommufd: Associate fault object with iommufd_hw_pgtable")
> Cc: stable@xxxxxxxxxxxxxxx
> Tested-by: Peiyang He <peiyang_he@xxxxxxxxxxxxxxxx>
> Assisted-by: Codex:gpt-5.6-sol
> Signed-off-by: Peiyang He <peiyang_he@xxxxxxxxxxxxxxxx>
> ---
>  drivers/iommu/io-pgfault.c     | 24 +++++++++++++++++++-----
>  drivers/iommu/iommufd/eventq.c |  2 ++
>  include/linux/iommu.h          |  5 +++++
>  3 files changed, 26 insertions(+), 5 deletions(-)

Applied to for-rc

Thanks,
Jason