Re: [PATCH] fanotify: Fix sys_fanotify_mark() on native x86-32

[Andy Lutomirski]

On Mon, Nov 30, 2020 at 2:31 PM Brian Gerst <brgerst@xxxxxxxxx> wrote:
>
> Commit 121b32a58a3a converted native x86-32 which take 64-bit arguments to
> use the compat handlers to allow conversion to passing args via pt_regs.
> sys_fanotify_mark() was however missed, as it has a general compat handler.
> Add a config option that will use the syscall wrapper that takes the split
> args for native 32-bit.
>
> Reported-by: Paweł Jasiak <pawel@xxxxxxxxxx>
> Fixes: 121b32a58a3a ("x86/entry/32: Use IA32-specific wrappers for syscalls taking 64-bit arguments")
> Signed-off-by: Brian Gerst <brgerst@xxxxxxxxx>
> ---
>  arch/Kconfig                       |  6 ++++++
>  arch/x86/Kconfig                   |  1 +
>  fs/notify/fanotify/fanotify_user.c | 17 +++++++----------
>  include/linux/syscalls.h           | 24 ++++++++++++++++++++++++
>  4 files changed, 38 insertions(+), 10 deletions(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 090ef3566c56..452cc127c285 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -1045,6 +1045,12 @@ config HAVE_STATIC_CALL_INLINE
>         bool
>         depends on HAVE_STATIC_CALL
>
> +config ARCH_SPLIT_ARG64
> +       bool
> +       help
> +          If a 32-bit architecture requires 64-bit arguments to be split into
> +          pairs of 32-bit arguemtns, select this option.

You misspelled arguments.  You might also want to clarify that, for
64-bit arches, this means that compat syscalls split their arguments.

Aside from that:

Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>