From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753431AbcHTBki (ORCPT ); Fri, 19 Aug 2016 21:40:38 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:35076 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751027AbcHTBkh (ORCPT ); Fri, 19 Aug 2016 21:40:37 -0400 From: Wei Yang To: tglx@linutronix.de, yinghai@kernel.org Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Wei Yang Subject: [PATCH] x86/e820: set end to (start + size - 1) in __append_e820_map() Date: Sat, 20 Aug 2016 01:40:13 +0000 Message-Id: <1471657213-31817-1-git-send-email-richard.weiyang@gmail.com> X-Mailer: git-send-email 2.5.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The (start, size) tuple represents a range [start, start + size - 1], which means "start" and "start + size - 1" should be compared to see whether the range overflows. For example, a range with (start, size) (0xffffffff fffffff0, 0x00000000 00000010) represents [0xffffffff fffffff0, 0xffffffff ffffffff] would be judged overflow in the original code, while actually it is not. This patch fixes this and makes sure it still works when size is zero. Signed-off-by: Wei Yang --- arch/x86/kernel/e820.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 621b501..871f186 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -388,11 +388,11 @@ static int __init __append_e820_map(struct e820entry *biosmap, int nr_map) while (nr_map) { u64 start = biosmap->addr; u64 size = biosmap->size; - u64 end = start + size; + u64 end = start + size - 1; u32 type = biosmap->type; /* Overflow in 64 bits? Ignore the memory map. */ - if (start > end) + if (start > end && likely(size)) return -1; e820_add_region(start, size, type); -- 1.7.9.5