From: Christoph Hellwig

Sent: 14 February 2022 17:01

On Mon, Feb 14, 2022 at 05:34:41PM +0100, Arnd Bergmann wrote:

quoted

From: Arnd Bergmann <arnd@arndb.de>

The get_user()/put_user() functions are meant to check for
access_ok(), while the __get_user()/__put_user() functions
don't.

This broke in 4.19 for nds32, when it gained an extraneous
check in __get_user(), but lost the check it needs in
__put_user().

Can we follow the lead of MIPS (which this was originally copied
from I think) and kill the pointless __get/put_user_check wrapper
that just obsfucate the code?

Is it possible to make all these architectures fall back to
a common definition somewhere?

Maybe they need to define ACCESS_OK_USER_LIMIT - which can be
different from TASK_SIZE.

There'll be a few special cases, but most architectures have
kernel addresses above userspace ones.

	David