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Date: Tue, 23 Mar 2010 09:34:09 +0800
Message-ID: <628d1651003221834g543e3e6cl4ea39c0886cb4ba1@mail.gmail.com>
Subject: Re: [PATCH] Netfilter: Fix integer overflow in net/ipv6/netfilter/ip6_tables.c
From: wzt wzt <wzt.wzt@gmail.com>
To: Patrick McHardy <kaber@trash.net>
Cc: linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org
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> 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.

        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.