linux-kernel - Re: [PATCH 2/2] mm: Add kvmalloc_ab_c and kvzalloc

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Date:   Sun, 29 Apr 2018 09:59:27 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Julia Lawall <julia.lawall@...6.fr>,
        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>,
        cocci@...teme.lip6.fr, Himanshu Jha <himanshujha199640@...il.com>
Subject: Re: [PATCH 2/2] mm: Add kvmalloc_ab_c and kvzalloc_struct

On Tue, Mar 13, 2018 at 11:32 AM, Matthew Wilcox <willy@...radead.org> wrote:
> On Tue, Mar 13, 2018 at 06:19:51PM +0100, Julia Lawall wrote:
>> On Thu, 8 Mar 2018, Matthew Wilcox wrote:
>> > On Thu, Mar 08, 2018 at 07:24:47AM +0100, Julia Lawall wrote:
>> > > Thanks.  So it's OK to replace kmalloc and kzalloc, even though they
>> > > didn't previously consider vmalloc and even though kmalloc doesn't zero?
>> >
>> > We'll also need to replace the corresponding places where those structs
>> > are freed with kvfree().  Can coccinelle handle that too?
>>
>> Is the use of vmalloc a necessary part of the design?  Or could there be a
>> non vmalloc versions for call sites that are already ok with that?
>
> We can also add kmalloc_struct() along with kmalloc_ab_c that won't fall
> back to vmalloc but just return NULL.

Did this ever happen? I'd also like to see kmalloc_array_3d() or
something that takes three size arguments. We have a lot of this
pattern too:

kmalloc(sizeof(foo) * A * B, gfp...)

And we could turn that into:

kmalloc_array_3d(sizeof(foo), A, B, gfp...)

-Kees


-- 
Kees Cook
Pixel Security