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

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Date:   Tue, 13 Mar 2018 19:35:44 +0100 (CET)
From:   Julia Lawall <julia.lawall@...6.fr>
To:     Matthew Wilcox <willy@...radead.org>
cc:     Kees Cook <keescook@...omium.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>,
        cocci@...teme.lip6.fr, Himanshu Jha <himanshujha199640@...il.com>
Subject: Re: [PATCH 2/2] mm: Add kvmalloc_ab_c and kvzalloc_struct



On Tue, 13 Mar 2018, Matthew Wilcox 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.

It could be safer than being sure to find all of the relevant kfrees.

julia