From patchwork Mon Jul 12 06:12:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 473783 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 02710C11F68 for ; Mon, 12 Jul 2021 07:31:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC3E161419 for ; Mon, 12 Jul 2021 07:31:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343869AbhGLHeA (ORCPT ); Mon, 12 Jul 2021 03:34:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:43440 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345493AbhGLH3y (ORCPT ); Mon, 12 Jul 2021 03:29:54 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 218A96052B; Mon, 12 Jul 2021 07:26:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626074812; bh=92RQ7ovfVPIika+3PGDd5//JInAuNVNk4o1IcirZSxM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z+Jca37D1yyWRQoQaBJd2rcuiDzsEskM6fL1lBc67H4HniKYKvzhLEOkLfxZEpyG1 RYdsSCZi62EzsE8gwG1kUbRoa7MuCSevGyrrXnA12jWNK6FR/goL8CQ2xwvEc7Eaop pAsKDXi6ZlhCU9hYlN+KQCteYMEqdkGPFu8dB2O0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dave Hansen , Thomas Gleixner , "Aneesh Kumar K.V" , Ram Pai , Sandipan Das , Florian Weimer , "Desnes A. Nunes do Rosario" , Ingo Molnar , Thiago Jung Bauermann , Michael Ellerman , Michal Hocko , Michal Suchanek , Shuah Khan , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 5.12 677/700] selftests/vm/pkeys: refill shadow register after implicit kernel write Date: Mon, 12 Jul 2021 08:12:40 +0200 Message-Id: <20210712061047.897155351@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060924.797321836@linuxfoundation.org> References: <20210712060924.797321836@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Dave Hansen [ Upstream commit 6039ca254979694c5362dfebadd105e286c397bb ] The pkey test code keeps a "shadow" of the pkey register around. This ensures that any bugs which might write to the register can be caught more quickly. Generally, userspace has a good idea when the kernel is going to write to the register. For instance, alloc_pkey() is passed a permission mask. The caller of alloc_pkey() can update the shadow based on the return value and the mask. But, the kernel can also modify the pkey register in a more sneaky way. For mprotect(PROT_EXEC) mappings, the kernel will allocate a pkey and write the pkey register to create an execute-only mapping. The kernel never tells userspace what key it uses for this. This can cause the test to fail with messages like: protection_keys_64.2: pkey-helpers.h:132: _read_pkey_reg: Assertion `pkey_reg == shadow_pkey_reg' failed. because the shadow was not updated with the new kernel-set value. Forcibly update the shadow value immediately after an mprotect(). Link: https://lkml.kernel.org/r/20210611164200.EF76AB73@viggo.jf.intel.com Fixes: 6af17cf89e99 ("x86/pkeys/selftests: Add PROT_EXEC test") Signed-off-by: Dave Hansen Signed-off-by: Thomas Gleixner Tested-by: Aneesh Kumar K.V Cc: Ram Pai Cc: Sandipan Das Cc: Florian Weimer Cc: "Desnes A. Nunes do Rosario" Cc: Ingo Molnar Cc: Thiago Jung Bauermann Cc: Michael Ellerman Cc: Michal Hocko Cc: Michal Suchanek Cc: Shuah Khan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- tools/testing/selftests/vm/protection_keys.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/tools/testing/selftests/vm/protection_keys.c b/tools/testing/selftests/vm/protection_keys.c index 356d62fca27f..87eecd5ba577 100644 --- a/tools/testing/selftests/vm/protection_keys.c +++ b/tools/testing/selftests/vm/protection_keys.c @@ -1448,6 +1448,13 @@ void test_implicit_mprotect_exec_only_memory(int *ptr, u16 pkey) ret = mprotect(p1, PAGE_SIZE, PROT_EXEC); pkey_assert(!ret); + /* + * Reset the shadow, assuming that the above mprotect() + * correctly changed PKRU, but to an unknown value since + * the actual alllocated pkey is unknown. + */ + shadow_pkey_reg = __read_pkey_reg(); + dprintf2("pkey_reg: %016llx\n", read_pkey_reg()); /* Make sure this is an *instruction* fault */