linux-kernel - Re: [PATCH 0/2] Add kvzalloc_struct to complement kvzalloc

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Message-ID: <CAGXu5jJdAJt3HK7FgaCyPRbXeFV-hJOrPodNnOkx=kCvSieK3w@mail.gmail.com>
Date:   Wed, 14 Feb 2018 11:23:47 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Joe Perches <joe@...ches.com>
Cc:     Matthew Wilcox <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH 0/2] Add kvzalloc_struct to complement kvzalloc_array

On Wed, Feb 14, 2018 at 10:47 AM, Joe Perches <joe@...ches.com> wrote:
> On Wed, 2018-02-14 at 10:26 -0800, Matthew Wilcox wrote:
>> From: Matthew Wilcox <mawilcox@...rosoft.com>
>>
>> We all know the perils of multiplying a value provided from userspace
>> by a constant and then allocating the resulting number of bytes.  That's
>> why we have kvmalloc_array(), so we don't have to think about it.
>> This solves the same problem when we embed one of these arrays in a
>> struct like this:
>>
>> struct {
>>       int n;
>>       unsigned long array[];
>> };
>
> I think expanding the number of allocation functions
> is not necessary.

I think removing common mispatterns in favor of overflow-protected
allocation functions makes sense.

-Kees

-- 
Kees Cook
Pixel Security