From: Xiaotian Feng <xtfeng@gmail.com>
To: wzt wzt <wzt.wzt@gmail.com>
Cc: Patrick McHardy <kaber@trash.net>,
linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org
Subject: Re: [PATCH] Netfilter: Fix integer overflow in net/ipv6/netfilter/ip6_tables.c
Date: Tue, 23 Mar 2010 11:05:40 +0800 [thread overview]
Message-ID: <7b6bb4a51003222005v5fd71c8ao7fd1d05fb1ef2d8b@mail.gmail.com> (raw)
In-Reply-To: <628d1651003221937q58ff39fel467636ab55531128@mail.gmail.com>
On Tue, Mar 23, 2010 at 10:37 AM, wzt wzt <wzt.wzt@gmail.com> 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 <xtfeng@gmail.com> wrote:
>> On Tue, Mar 23, 2010 at 9:34 AM, wzt wzt <wzt.wzt@gmail.com> 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/
>>>
>>
>
next prev parent reply other threads:[~2010-03-23 3:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-20 14:32 [PATCH] Netfilter: Fix integer overflow in net/ipv6/netfilter/ip6_tables.c wzt.wzt
2010-03-22 17:07 ` Patrick McHardy
2010-03-23 1:34 ` wzt wzt
2010-03-23 2:29 ` Xiaotian Feng
2010-03-23 2:37 ` wzt wzt
2010-03-23 3:04 ` Jan Engelhardt
2010-03-23 3:48 ` wzt wzt
2010-03-23 4:49 ` Xiaotian Feng
2010-03-23 5:49 ` wzt wzt
2010-03-23 3:05 ` Xiaotian Feng [this message]
2010-03-23 3:11 ` wzt wzt
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