On Sun, May 21, 2017 at 2:37 PM, Linus Torvalds
<torva...@linux-foundation.org> wrote:
>
> I'm pretty sure there's a reason we added support for it on x86-32,
> because there are structures that use __u64 and fill things one entry
> at a time.
Did an "allyesconfig" build on 32-bit x86, and looked at who uses the
8-byte get_user/put_user cases:
__get_user_8:
i915_perf_open_ioctl
__put_user_8:
snapshot_ioctl
sys_sendfile64
timerfd_read
eventfd_read
userfaultfd_ioctl
kpagecgroup_read
kpagecount_read
kpageflags_read
__ncp_ioctl
blkdev_ioctl
drm_mode_object_get_properties
drm_mode_getproperty_ioctl
efi_test_ioctl
params_to_user
__rds_rdma_map
so it's not common, but both do get used.
Would any of those be changed to the unsafe versions? Maybe not. But I
think we're better off being consistent.
We basically allow all kernel integer types to be used for
put/get_user(), and the fact that some architectures don't support
them is just a quirk of that architecture, not a sign that it
shouldn't be done.
Linus
