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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 4BDE7C0044C for ; Mon, 29 Oct 2018 18:35:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 166722064C for ; Mon, 29 Oct 2018 18:35:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 166722064C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729402AbeJ3DZM (ORCPT ); Mon, 29 Oct 2018 23:25:12 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:52566 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728898AbeJ3DZL (ORCPT ); Mon, 29 Oct 2018 23:25:11 -0400 Received: from tmo-115-37.customers.d1-online.com ([80.187.115.37] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1gHCNP-0000mo-NM; Mon, 29 Oct 2018 19:34:59 +0100 Date: Mon, 29 Oct 2018 19:34:58 +0100 (CET) From: Thomas Gleixner To: Dan Carpenter cc: Dave Hansen , Andy Lutomirski , Peter Zijlstra , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: Re: [PATCH] x86/ioremap: tighten integer overflow checking In-Reply-To: <20181025061633.t32bxslxj3h7jv2x@kili.mountain> Message-ID: References: <20181025061633.t32bxslxj3h7jv2x@kili.mountain> 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 Dan, On Thu, 25 Oct 2018, Dan Carpenter wrote: > The current check is a bit off in the case where "phys_addr + size" > wraps to zero because then "last_addr" is set to ULONG_MAX which is >= > phys_addr. > > Signed-off-by: Dan Carpenter > --- > arch/x86/mm/ioremap.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c > index 5378d10f1d31..ee43df3ebe66 100644 > --- a/arch/x86/mm/ioremap.c > +++ b/arch/x86/mm/ioremap.c > @@ -146,9 +146,9 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr, > void __iomem *ret_addr; > > /* Don't allow wraparound or zero size */ > - last_addr = phys_addr + size - 1; > - if (!size || last_addr < phys_addr) > + if (!size || phys_addr + size < phys_addr) Assume the following (resource_size_t == u32, which is the case when CONFIG_PHYS_ADDR_T_64BIT=n): phys_addr = 0xFFFF0000 size = 0x00010000 sum = 0x00000000 which is < phys_addr But the existing code does: last_addr = phys_addr + size - 1 = 0xFFFFFFFF which is correct. last_addr is the last valid address in the to be remapped range starting @phys_addr. Thanks, tglx