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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 5794FC3A5A1 for ; Wed, 28 Aug 2019 21:55:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 363C922DA7 for ; Wed, 28 Aug 2019 21:55:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727562AbfH1VzB (ORCPT ); Wed, 28 Aug 2019 17:55:01 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:48588 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727385AbfH1Vy6 (ORCPT ); Wed, 28 Aug 2019 17:54:58 -0400 Received: from p5de0b6c5.dip0.t-ipconnect.de ([93.224.182.197] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1i35u4-0005EZ-59; Wed, 28 Aug 2019 23:54:56 +0200 Date: Wed, 28 Aug 2019 23:54:55 +0200 (CEST) From: Thomas Gleixner To: LKML cc: x86@kernel.org, Song Liu , Joerg Roedel , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Rik van Riel Subject: [patch V3 1/2] x86/mm/pti: Handle unaligned address gracefully in pti_clone_pagetable() In-Reply-To: Message-ID: References: <20190828142445.454151604@linutronix.de> <20190828143123.971884723@linutronix.de> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Song Liu pti_clone_pmds() assumes that the supplied address is either: - properly PUD/PMD aligned or - the address is actually mapped which means that independently of the mapping level (PUD/PMD/PTE) the next higher mapping exists. If that's not the case the unaligned address can be incremented by PUD or PMD size incorrectly. All callers supply mapped and/or aligned addresses, but for the sake of robustness it's better to handle that case properly and to emit a warning. [ tglx: Rewrote changelog and added WARN_ON_ONCE() ] Signed-off-by: Song Liu Signed-off-by: Thomas Gleixner --- V2: Negate P[UM]D_MASK for checking whether the offset part is 0 V3: Fix changelog --- arch/x86/mm/pti.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -330,13 +330,15 @@ pti_clone_pgtable(unsigned long start, u pud = pud_offset(p4d, addr); if (pud_none(*pud)) { - addr += PUD_SIZE; + WARN_ON_ONCE(addr & ~PUD_MASK); + addr = round_up(addr + 1, PUD_SIZE); continue; } pmd = pmd_offset(pud, addr); if (pmd_none(*pmd)) { - addr += PMD_SIZE; + WARN_ON_ONCE(addr & ~PMD_MASK); + addr = round_up(addr + 1, PMD_SIZE); continue; }