On Thu, Nov 26, 2020 at 7:52 AM Jan Kara <jack@xxxxxxx> wrote:
>
> Commit converting syscalls taking 64-bit arguments to new scheme of compat
> handlers omitted converting fanotify_mark(2) which then broke the
> syscall for 32-bit x86 builds. Add missed conversion. It is somewhat
> cumbersome since we need to keep the original compat handler for all the
> other 32-bit archs.
>
This is stupendously ugly. I'm not really sure how this is supposed
to work on any 32-bit arch. I'm also not sure whether we should
expect the SYSCALL_DEFINE macros to figure this out by themselves.
At the very least, the native arm 32 and arm64 compat cases should get tested.
Al and Christoph, you're probably a lot more familiar than I am with
the nasty details of syscall ABI with 64-bit arguments.
> CC: Brian Gerst <brgerst@xxxxxxxxx>
> Suggested-by: Borislav Petkov <bp@xxxxxxx>
> Reported-by: Paweł Jasiak <pawel@xxxxxxxxxx>
> Reported-and-tested-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
> Fixes: 121b32a58a3a ("x86/entry/32: Use IA32-specific wrappers for syscalls taking 64-bit arguments")
> CC: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
> arch/x86/entry/syscalls/syscall_32.tbl | 2 +-
> fs/notify/fanotify/fanotify_user.c | 7 ++++++-
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> I plan to queue this fix into my tree next week. I'd be happy if someone with
> x86 ABI knowledge checks whether I've got the patch right (especially various
> config variants) because it was mostly a guesswork of me & Boris ;). Thanks!
>
> diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
> index 0d0667a9fbd7..b2ec6ff88307 100644
> --- a/arch/x86/entry/syscalls/syscall_32.tbl
> +++ b/arch/x86/entry/syscalls/syscall_32.tbl
> @@ -350,7 +350,7 @@
> 336 i386 perf_event_open sys_perf_event_open
> 337 i386 recvmmsg sys_recvmmsg_time32 compat_sys_recvmmsg_time32
> 338 i386 fanotify_init sys_fanotify_init
> -339 i386 fanotify_mark sys_fanotify_mark compat_sys_fanotify_mark
> +339 i386 fanotify_mark sys_ia32_fanotify_mark
> 340 i386 prlimit64 sys_prlimit64
> 341 i386 name_to_handle_at sys_name_to_handle_at
> 342 i386 open_by_handle_at sys_open_by_handle_at compat_sys_open_by_handle_at
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 3e01d8f2ab90..ba38f0fec4d0 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -1292,8 +1292,13 @@ SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
> return do_fanotify_mark(fanotify_fd, flags, mask, dfd, pathname);
> }
>
> -#ifdef CONFIG_COMPAT
> +#if defined(CONFIG_COMPAT) || defined(CONFIG_X86_32) || \
> + defined(CONFIG_IA32_EMULATION)
> +#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
> +SYSCALL_DEFINE6(ia32_fanotify_mark,
> +#elif CONFIG_COMPAT
> COMPAT_SYSCALL_DEFINE6(fanotify_mark,
> +#endif
> int, fanotify_fd, unsigned int, flags,
> __u32, mask0, __u32, mask1, int, dfd,
> const char __user *, pathname)
> --
> 2.16.4
>
