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 X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5057FC4167B for ; Thu, 10 Dec 2020 00:24:04 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D1AB922A84 for ; Thu, 10 Dec 2020 00:24:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D1AB922A84 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 11D476B0036; Wed, 9 Dec 2020 19:24:03 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0CE356B005D; Wed, 9 Dec 2020 19:24:03 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F252C6B0068; Wed, 9 Dec 2020 19:24:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0056.hostedemail.com [216.40.44.56]) by kanga.kvack.org (Postfix) with ESMTP id DCF3D6B0036 for ; Wed, 9 Dec 2020 19:24:02 -0500 (EST) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 9FDD7180AD807 for ; Thu, 10 Dec 2020 00:24:02 +0000 (UTC) X-FDA: 77575475124.14.goose53_5903af3273f3 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin14.hostedemail.com (Postfix) with ESMTP id 825BC1822987A for ; Thu, 10 Dec 2020 00:24:02 +0000 (UTC) X-HE-Tag: goose53_5903af3273f3 X-Filterd-Recvd-Size: 1829 Received: from ozlabs.org (ozlabs.org [203.11.71.1]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Thu, 10 Dec 2020 00:24:01 +0000 (UTC) Received: by ozlabs.org (Postfix, from userid 1034) id 4CrvmF6kJfz9sWL; Thu, 10 Dec 2020 11:23:57 +1100 (AEDT) From: Michael Ellerman To: akpm@linux-foundation.org, hch@lst.de, Michael Ellerman , Christophe Leroy , viro@zeniv.linux.org.uk, Benjamin Herrenschmidt , Paul Mackerras Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org In-Reply-To: <18bcb456d32a3e74f5ae241fd6f1580c092d07f5.1607360230.git.christophe.leroy@csgroup.eu> References: <18bcb456d32a3e74f5ae241fd6f1580c092d07f5.1607360230.git.christophe.leroy@csgroup.eu> Subject: Re: [PATCH v2] powerpc/mm: Fix KUAP warning by providing copy_from_kernel_nofault_allowed() Message-Id: <160755982586.1285738.12667869391229651303.b4-ty@ellerman.id.au> Date: Thu, 10 Dec 2020 11:23:57 +1100 (AEDT) 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 Mon, 7 Dec 2020 16:58:01 +0000 (UTC), Christophe Leroy wrote: > Since commit c33165253492 ("powerpc: use non-set_fs based maccess > routines"), userspace access is not granted anymore when using > copy_from_kernel_nofault() > > However, kthread_probe_data() uses copy_from_kernel_nofault() > to check validity of pointers. When the pointer is NULL, > it points to userspace, leading to a KUAP fault and triggering > the following big hammer warning many times when you request > a sysrq "show task": > > [...] Applied to powerpc/fixes. [1/1] powerpc/mm: Fix KUAP warning by providing copy_from_kernel_nofault_allowed() https://git.kernel.org/powerpc/c/5eedf9fe8db23313df104576845cec5f481b9b60 cheers