From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8ADEFC433F5 for ; Fri, 18 Feb 2022 06:35:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2056E6B007B; Fri, 18 Feb 2022 01:35:53 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 18F726B007D; Fri, 18 Feb 2022 01:35:53 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0303D6B007E; Fri, 18 Feb 2022 01:35:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0078.hostedemail.com [216.40.44.78]) by kanga.kvack.org (Postfix) with ESMTP id E62B16B007B for ; Fri, 18 Feb 2022 01:35:52 -0500 (EST) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id AA975180AC329 for ; Fri, 18 Feb 2022 06:35:52 +0000 (UTC) X-FDA: 79154940144.26.993A2BF Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf14.hostedemail.com (Postfix) with ESMTP id 1E7A1100006 for ; Fri, 18 Feb 2022 06:35:51 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 4DEC168BFE; Fri, 18 Feb 2022 07:35:49 +0100 (CET) Date: Fri, 18 Feb 2022 07:35:49 +0100 From: Christoph Hellwig To: 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, viro@zeniv.linux.org.uk, linux@armlinux.org.uk, will@kernel.org, guoren@kernel.org, bcain@codeaurora.org, geert@linux-m68k.org, monstr@monstr.eu, tsbogend@alpha.franken.de, nickhu@andestech.com, green.hu@gmail.com, dinguyen@kernel.org, shorne@gmail.com, deller@gmx.de, mpe@ellerman.id.au, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, hca@linux.ibm.com, dalias@libc.org, davem@davemloft.net, richard@nod.at, x86@kernel.org, jcmvbkbc@gmail.com, ebiederm@xmission.com, akpm@linux-foundation.org, ardb@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org Subject: Re: [PATCH v2 14/18] lib/test_lockup: fix kernel pointer check for separate address spaces Message-ID: <20220218063549.GJ22576@lst.de> References: <20220216131332.1489939-1-arnd@kernel.org> <20220216131332.1489939-15-arnd@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220216131332.1489939-15-arnd@kernel.org> User-Agent: Mutt/1.5.17 (2007-11-01) X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 1E7A1100006 X-Stat-Signature: d3p1u9xdscfhd7d7ybj4hazrkmuzgzs1 Authentication-Results: imf14.hostedemail.com; dkim=none; dmarc=none; spf=none (imf14.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de X-HE-Tag: 1645166151-306011 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Feb 16, 2022 at 02:13:28PM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann > > test_kernel_ptr() uses access_ok() to figure out if a given address > points to user space instead of kernel space. However on architectures > that set CONFIG_ALTERNATE_USER_ADDRESS_SPACE, a pointer can be valid > for both, and the check always fails because access_ok() returns true. > > Make the check for user space pointers conditional on the type of > address space layout. What is this code even trying to do? It looks extremly broken.