From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiaotian Feng Subject: Re: [PATCH] Netfilter: Fix integer overflow in net/ipv6/netfilter/ip6_tables.c Date: Tue, 23 Mar 2010 11:05:40 +0800 Message-ID: <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> 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: wzt wzt Return-path: In-Reply-To: <628d1651003221937q58ff39fel467636ab55531128@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netfilter-devel.vger.kernel.org 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 0x7fffff= ff, > 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 "multiplic= ation"? >> 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 wr= ote: >> 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 wi= th >>>> 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 0x7fff= ffff, >>> 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_entr= ies) + get.size) { >>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0duprintf("ge= t_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 -EINV= AL; >>> =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-ker= nel" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at =C2=A0http://vger.kernel.org/majordomo-info.= html >>> Please read the FAQ at =C2=A0http://www.tux.org/lkml/ >>> >> >