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=-5.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 29298C31E5B for ; Mon, 17 Jun 2019 21:32:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EE3A220657 for ; Mon, 17 Jun 2019 21:32:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560807163; bh=DVGuKqqoeaNYdJr7IUL6NDCwqpGr5Pq/T3n4rVcY34Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UVX08oFjGsiewxU74a5XkffOveeD6uUSNfziMcUWn/MafUdF6UuwJpngLkOvRS0JE s0sIbVAReulyZM7dbblHrXqXfdIN1aP5397sKP0JYiYT1kJ/yLiDA8lZXGHRfGSriU cNUytEtTG1x7NhMKbHtjaHki9zO9JLWstfHb7re0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730362AbfFQV1P (ORCPT ); Mon, 17 Jun 2019 17:27:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:54078 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730020AbfFQV1L (ORCPT ); Mon, 17 Jun 2019 17:27:11 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8331E20673; Mon, 17 Jun 2019 21:27:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560806831; bh=DVGuKqqoeaNYdJr7IUL6NDCwqpGr5Pq/T3n4rVcY34Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uQoY7v5MVPw9vZ5y59EKlDzCCZN0TVs68jtIbJVYOk1A04L8RwWvM0mxCQ7XgD0Bd kRbmrA9l1Q3UQ7c+hVdIBko6QAxB6Er1Bl1CjKWsofUN+YnozRJjBNb6mONtwargB0 t7UNvFg8QizxdHTv0LB3S16pgFJO1GR1z5Z8Dj/A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Kirill A. Shutemov" , Andrey Ryabinin , Thomas Gleixner , Borislav Petkov , "H. Peter Anvin" , Alexander Potapenko , Dmitry Vyukov , kasan-dev@googlegroups.com Subject: [PATCH 4.19 70/75] x86/kasan: Fix boot with 5-level paging and KASAN Date: Mon, 17 Jun 2019 23:10:21 +0200 Message-Id: <20190617210755.943656383@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190617210752.799453599@linuxfoundation.org> References: <20190617210752.799453599@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andrey Ryabinin commit f3176ec9420de0c385023afa3e4970129444ac2f upstream. Since commit d52888aa2753 ("x86/mm: Move LDT remap out of KASLR region on 5-level paging") kernel doesn't boot with KASAN on 5-level paging machines. The bug is actually in early_p4d_offset() and introduced by commit 12a8cc7fcf54 ("x86/kasan: Use the same shadow offset for 4- and 5-level paging") early_p4d_offset() tries to convert pgd_val(*pgd) value to a physical address. This doesn't make sense because pgd_val() already contains the physical address. It did work prior to commit d52888aa2753 because the result of "__pa_nodebug(pgd_val(*pgd)) & PTE_PFN_MASK" was the same as "pgd_val(*pgd) & PTE_PFN_MASK". __pa_nodebug() just set some high bits which were masked out by applying PTE_PFN_MASK. After the change of the PAGE_OFFSET offset in commit d52888aa2753 __pa_nodebug(pgd_val(*pgd)) started to return a value with more high bits set and PTE_PFN_MASK wasn't enough to mask out all of them. So it returns a wrong not even canonical address and crashes on the attempt to dereference it. Switch back to pgd_val() & PTE_PFN_MASK to cure the issue. Fixes: 12a8cc7fcf54 ("x86/kasan: Use the same shadow offset for 4- and 5-level paging") Reported-by: Kirill A. Shutemov Signed-off-by: Andrey Ryabinin Signed-off-by: Thomas Gleixner Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: kasan-dev@googlegroups.com Cc: stable@vger.kernel.org Cc: Link: https://lkml.kernel.org/r/20190614143149.2227-1-aryabinin@virtuozzo.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/kasan_init_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -198,7 +198,7 @@ static inline p4d_t *early_p4d_offset(pg if (!pgtable_l5_enabled()) return (p4d_t *)pgd; - p4d = __pa_nodebug(pgd_val(*pgd)) & PTE_PFN_MASK; + p4d = pgd_val(*pgd) & PTE_PFN_MASK; p4d += __START_KERNEL_map - phys_base; return (p4d_t *)p4d + p4d_index(addr); }