From mboxrd@z Thu Jan 1 00:00:00 1970 From: wzt wzt Subject: Re: [PATCH] Netfilter: Fix integer overflow in net/ipv6/netfilter/ip6_tables.c Date: Tue, 23 Mar 2010 11:11:22 +0800 Message-ID: <628d1651003222011v2389fc68u7ba009ae4b781884@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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Patrick McHardy , linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org To: Xiaotian Feng Return-path: 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 In-Reply-To: <7b6bb4a51003222005v5fd71c8ao7fd1d05fb1ef2d8b@mail.gmail.com> Sender: netfilter-devel-owner@vger.kernel.org List-ID: > get.size is unsigned int, UINT_MAX is 0x FFFFFFFF, not 0x7FFFFFFF > And you're metioning "addition", then why you're checking as "multipl= ication"? 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 wrot= e: > On Tue, Mar 23, 2010 at 10:37 AM, wzt wzt wrote: >>> Patrick's point is that you're using "if (get.size >=3D INT_MAX / >>> sizeof(struct ipt_get_entries))" >>> So, did you find any chance that get.size * sizeof(struct >>> ipt_get_entries) >=3D INT_MAX ? >>> >> would you carefully read my explain??? >> get.size is copy from the user space, =C2=A0it can be set as 0x7ffff= fff, >> 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 "multipl= ication"? > >>> And, for the addition overflow, can it be caught by >>> >>> "if (*len !=3D sizeof(struct ipt_get_entries) + get.size)" =C2=A0??= ? >>> >> 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 w= rote: >>> 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 w= ith >>>>> sizeof(struct ipt_get_entries) >>>> That's the integer overflow i pointed. >>>> get.size is copy from the user space, =C2=A0it can be set as 0x7ff= fffff, >>>> addition with sizeof(struct ipt_get_entries) can be overflow. >>> >>> Patrick's point is that you're using "if (get.size >=3D INT_MAX / >>> sizeof(struct ipt_get_entries))" >>> So, did you find any chance that get.size * sizeof(struct >>> ipt_get_entries) >=3D INT_MAX ? >>> >>> And, for the addition overflow, can it be caught by >>> >>> "if (*len !=3D sizeof(struct ipt_get_entries) + get.size)" =C2=A0??= ? >>> >>>> >>>> =C2=A0 =C2=A0 =C2=A0 =C2=A0if (*len !=3D sizeof(struct ipt_get_ent= ries) + get.size) { >>>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0duprintf("g= et_entries: %u !=3D %zu\n", >>>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 *len, sizeof(get) + get.size); >>>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0return -EIN= VAL; >>>> =C2=A0 =C2=A0 =C2=A0 =C2=A0} >>>> >>>> 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-ke= rnel" in >>>> the body of a message to majordomo@vger.kernel.org >>>> More majordomo info at =C2=A0http://vger.kernel.org/majordomo-info= =2Ehtml >>>> Please read the FAQ at =C2=A0http://www.tux.org/lkml/ >>>> >>> >> > -- To unsubscribe from this list: send the line "unsubscribe netfilter-dev= el" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html