linux-kernel - Re: [PATCH v2] netfilter: ipset: Fix overflow before widen in the bitmap_ip

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Message-ID: <Y777m3reT6s1sCnD@salvia>
Date:   Wed, 11 Jan 2023 19:10:35 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Simon Horman <simon.horman@...igine.com>
Cc:     Gavrilov Ilia <Ilia.Gavrilov@...otecs.ru>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "netfilter-devel@...r.kernel.org" <netfilter-devel@...r.kernel.org>,
        "coreteam@...filter.org" <coreteam@...filter.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "lvc-project@...uxtesting.org" <lvc-project@...uxtesting.org>
Subject: Re: [PATCH v2] netfilter: ipset: Fix overflow before widen in the
 bitmap_ip_create() function.

On Wed, Jan 11, 2023 at 01:00:53PM +0100, Simon Horman wrote:
> On Wed, Jan 11, 2023 at 11:57:39AM +0000, Gavrilov Ilia wrote:
> > [You don't often get email from ilia.gavrilov@...otecs.ru. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> > 
> > When first_ip is 0, last_ip is 0xFFFFFFFF, and netmask is 31, the value of
> > an arithmetic expression 2 << (netmask - mask_bits - 1) is subject
> > to overflow due to a failure casting operands to a larger data type
> > before performing the arithmetic.
> > 
> > Note that it's harmless since the value will be checked at the next step.
> > 
> > Found by InfoTeCS on behalf of Linux Verification Center
> > (linuxtesting.org) with SVACE.
> > 
> > Fixes: b9fed748185a ("netfilter: ipset: Check and reject crazy /0 input parameters")
> > Signed-off-by: Ilia.Gavrilov <Ilia.Gavrilov@...otecs.ru>
> 
> Reviewed-by: Simon Horman <simon.horman@...igine.com>

Applied, thanks