On Wed, Aug 09, 2023 at 05:02:47PM -0400, Stefan Hajnoczi wrote: > The memory layout of struct vfio_iommu_type1_info is > architecture-dependent due to a u64 field and a struct size that is not > a multiple of 8 bytes: > - On x86_64 the struct size is padded to a multiple of 8 bytes. > - On x32 the struct size is only a multiple of 4 bytes, not 8. > - Other architectures may vary. > > Use __aligned_u64 to make memory layout consistent. This reduces the > chance of holes that result in an information leak and the chance that > 32-bit userspace on a 64-bit kernel breakage. > > This patch increases the struct size on x32 but this is safe because of > the struct's argsz field. The kernel may grow the struct as long as it > still supports smaller argsz values from userspace (e.g. applications > compiled against older kernel headers). > > Suggested-by: Jason Gunthorpe <jgg@xxxxxxxx> > Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx> > --- > include/uapi/linux/vfio.h | 3 ++- > drivers/vfio/vfio_iommu_type1.c | 11 ++--------- > 2 files changed, 4 insertions(+), 10 deletions(-) Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx> Jason
