mbox series

[0/4] vfio: use __aligned_u64 for ioctl structs

Message ID 20230809210248.2898981-1-stefanha@redhat.com (mailing list archive)
Headers show
Series vfio: use __aligned_u64 for ioctl structs | expand

Message

Stefan Hajnoczi Aug. 9, 2023, 9:02 p.m. UTC 
Jason Gunthorpe <jgg@ziepe.ca> pointed out that u64 VFIO ioctl struct fields
have architecture-dependent alignment. iommufd already uses __aligned_u64 to
avoid this problem.

Reasons for using __aligned_u64 include avoiding potential information leaks
due to architecture-specific holes in structs and 32-bit userspace on 64-bit
kernel ioctl compatibility issues. See the __aligned_u64 typedef in
<uapi/linux/types.h> for details.

This series modifies the VFIO ioctl structs to use __aligned_u64. Some of the
changes preserve the existing memory layout on all architectures, so I put them
together into the first patch. The remaining patches are for structs where
explanation is necessary about why changing the memory layout does not break
the uapi.

Stefan Hajnoczi (4):
  vfio: trivially use __aligned_u64 for ioctl structs
  vfio: use __aligned_u64 in struct vfio_device_gfx_plane_info
  vfio: use __aligned_u64 in struct vfio_iommu_type1_info
  vfio: use __aligned_u64 in struct vfio_device_ioeventfd

 include/uapi/linux/vfio.h        | 27 +++++++++++++++------------
 drivers/gpu/drm/i915/gvt/kvmgt.c |  4 +++-
 drivers/vfio/vfio_iommu_type1.c  | 11 ++---------
 samples/vfio-mdev/mbochs.c       |  6 ++++--
 samples/vfio-mdev/mdpy.c         |  4 +++-
 5 files changed, 27 insertions(+), 25 deletions(-)