From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754017Ab0CWDLZ (ORCPT ); Mon, 22 Mar 2010 23:11:25 -0400 Received: from mail-gy0-f174.google.com ([209.85.160.174]:61360 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752137Ab0CWDLX convert rfc822-to-8bit (ORCPT ); Mon, 22 Mar 2010 23:11:23 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=EDm+h+W7ctg7a/e1PxCLeC26ntmWREuiUuKVVGF7hzvrFDQn06PgWOEHwq4j/dlFOw d95Ra801v32rI+7Kxuv8XbJiC1G7A9dJyntZVuZlwFz9skuAqVH5kSitu/6DVlt+VT6y 7X3sLWEnQOd0Gr62tpKmiaZgSQUaJt4LjC6lk= MIME-Version: 1.0 In-Reply-To: <7b6bb4a51003222005v5fd71c8ao7fd1d05fb1ef2d8b@mail.gmail.com> References: <20100320143240.GB2942@localhost.localdomain> <4BA7A3CF.8070503@trash.net> <628d1651003221834g543e3e6cl4ea39c0886cb4ba1@mail.gmail.com> <7b6bb4a51003221929i16673523nd5f558ccbaace397@mail.gmail.com> <628d1651003221937q58ff39fel467636ab55531128@mail.gmail.com> <7b6bb4a51003222005v5fd71c8ao7fd1d05fb1ef2d8b@mail.gmail.com> Date: Tue, 23 Mar 2010 11:11:22 +0800 Message-ID: <628d1651003222011v2389fc68u7ba009ae4b781884@mail.gmail.com> Subject: Re: [PATCH] Netfilter: Fix integer overflow in net/ipv6/netfilter/ip6_tables.c From: wzt wzt To: Xiaotian Feng Cc: Patrick McHardy , linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > get.size is unsigned int, UINT_MAX is 0x FFFFFFFF, not 0x7FFFFFFF > And you're metioning "addition", then why you're checking as "multiplication"? oh, my falut:( the patch is multiplication check, not addition check. thanks for helping me:) On Tue, Mar 23, 2010 at 11:05 AM, Xiaotian Feng wrote: > On Tue, Mar 23, 2010 at 10:37 AM, wzt wzt wrote: >>> Patrick's point is that you're using "if (get.size >= INT_MAX / >>> sizeof(struct ipt_get_entries))" >>> So, did you find any chance that get.size * sizeof(struct >>> ipt_get_entries) >= INT_MAX ? >>> >> would you carefully read my explain??? >> get.size is copy from the user space,  it can be set as 0x7fffffff, >> addition with sizeof(struct ipt_get_entries) can be overflow. >> > > get.size is unsigned int, UINT_MAX is 0x FFFFFFFF, not 0x7FFFFFFF > And you're metioning "addition", then why you're checking as "multiplication"? > >>> And, for the addition overflow, can it be caught by >>> >>> "if (*len != sizeof(struct ipt_get_entries) + get.size)"  ??? >>> >> sizeof(struct ipt_get_entries) + get.size can be overflow as *len, >> get.size is control by user space with copy_from_user(). > > >> >> On Tue, Mar 23, 2010 at 10:29 AM, Xiaotian Feng wrote: >>> On Tue, Mar 23, 2010 at 9:34 AM, wzt wzt wrote: >>>>> I can see that the size might cause an overflow in the addition with >>>>> sizeof(struct ipt_get_entries) >>>> That's the integer overflow i pointed. >>>> get.size is copy from the user space,  it can be set as 0x7fffffff, >>>> addition with sizeof(struct ipt_get_entries) can be overflow. >>> >>> Patrick's point is that you're using "if (get.size >= INT_MAX / >>> sizeof(struct ipt_get_entries))" >>> So, did you find any chance that get.size * sizeof(struct >>> ipt_get_entries) >= INT_MAX ? >>> >>> And, for the addition overflow, can it be caught by >>> >>> "if (*len != sizeof(struct ipt_get_entries) + get.size)"  ??? >>> >>>> >>>>        if (*len != sizeof(struct ipt_get_entries) + get.size) { >>>>                duprintf("get_entries: %u != %zu\n", >>>>                         *len, sizeof(get) + get.size); >>>>                return -EINVAL; >>>>        } >>>> >>>> so, check get.size max value before addition with sizeof(struct >>>> ipt_get_entries) to prevent the integer overflow. >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >>>> the body of a message to majordomo@vger.kernel.org >>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html >>>> Please read the FAQ at  http://www.tux.org/lkml/ >>>> >>> >> >