From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Laight Subject: RE: [PATCH 03/14] nds32: fix access_ok() checks in get/put_user Date: Mon, 14 Feb 2022 17:10:05 +0000 Message-ID: <8a6e309687d647e3aef8a88bdb0922af@AcuMS.aculab.com> References: <20220214163452.1568807-1-arnd@kernel.org> <20220214163452.1568807-4-arnd@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: Content-Language: en-US List-ID: Content-Type: text/plain; charset="us-ascii" To: 'Christoph Hellwig' , Arnd Bergmann Cc: Linus Torvalds , Christoph Hellwig , "linux-arch@vger.kernel.org" , "linux-mm@kvack.org" , "linux-api@vger.kernel.org" , "arnd@arndb.de" , "linux-kernel@vger.kernel.org" , "mark.rutland@arm.com" , "dalias@libc.org" , "linux-ia64@vger.kernel.org" , "linux-sh@vger.kernel.org" , "peterz@infradead.org" , "jcmvbkbc@gmail.com" , "guoren@kernel.org" , "sparclinux@vger.kernel.org" , "linux-hexagon@vger.kernel.org" From: Christoph Hellwig > Sent: 14 February 2022 17:01 > > On Mon, Feb 14, 2022 at 05:34:41PM +0100, Arnd Bergmann wrote: > > From: Arnd Bergmann > > > > 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