Re: [PATCH] Netfilter: Fix integer overflow in net/ipv6/netfilter/ip6_tables.c

[Xiaotian Feng]

On Tue, Mar 23, 2010 at 9:34 AM, wzt wzt <wzt.wzt@xxxxxxxxx> 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, Âit 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)"  ???

>
> Â Â Â Âif (*len != sizeof(struct ipt_get_entries) + get.size) {
> Â Â Â Â Â Â Â Âduprintf("get_entries: %u != %zu\n",
> Â Â Â Â Â Â Â Â Â Â Â Â *len, sizeof(get) + get.size);
> Â Â Â Â Â Â Â Âreturn -EINVAL;
> Â Â Â Â}
>
> so, check get.size max value before addition with sizeof(struct
> ipt_get_entries) to prevent the integer overflow.
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