From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753949Ab0CWDFm (ORCPT ); Mon, 22 Mar 2010 23:05:42 -0400 Received: from mail-qy0-f182.google.com ([209.85.221.182]:54080 "EHLO mail-qy0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752122Ab0CWDFl convert rfc822-to-8bit (ORCPT ); Mon, 22 Mar 2010 23:05:41 -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=DinsJdnd6ZJNL8pzoxQcLmmdyeSx6oPB5SNo+W+nVNtL7q7o2rLgiGARqyeUnA7s0J 56ZoHkdXrjqQ8wRzXR95V/wn5ysI5k2RCiCjckTmdSZ8hi3B4KssMn5+hSbvPckHEdNj 4zuWFgQMOxfk/d6oqxArXDf/tv/bZCVzB9P+0= MIME-Version: 1.0 In-Reply-To: <628d1651003221937q58ff39fel467636ab55531128@mail.gmail.com> References: <20100320143240.GB2942@localhost.localdomain> <4BA7A3CF.8070503@trash.net> <628d1651003221834g543e3e6cl4ea39c0886cb4ba1@mail.gmail.com> <7b6bb4a51003221929i16673523nd5f558ccbaace397@mail.gmail.com> <628d1651003221937q58ff39fel467636ab55531128@mail.gmail.com> Date: Tue, 23 Mar 2010 11:05:40 +0800 Message-ID: <7b6bb4a51003222005v5fd71c8ao7fd1d05fb1ef2d8b@mail.gmail.com> Subject: Re: [PATCH] Netfilter: Fix integer overflow in net/ipv6/netfilter/ip6_tables.c From: Xiaotian Feng To: wzt wzt 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 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/ >>> >> >