linux-kernel - Re: [PATCH 6/7] lkdtm: crash on overwriting protected pmalloc var

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Message-ID: <2664691b-4d48-1701-8dae-774ec7733f61@gmail.com>
Date:   Wed, 7 Mar 2018 09:26:55 -0800
From:   J Freyensee <why2jjj.linux@...il.com>
To:     Igor Stoppa <igor.stoppa@...wei.com>, david@...morbit.com,
        willy@...radead.org, keescook@...omium.org, mhocko@...nel.org
Cc:     labbott@...hat.com, linux-security-module@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH 6/7] lkdtm: crash on overwriting protected pmalloc var



On 3/7/18 5:18 AM, Igor Stoppa wrote:
>
> On 06/03/18 19:20, J Freyensee wrote:
>
>> On 2/28/18 12:06 PM, Igor Stoppa wrote:
> [...]
>
>>>    void __init lkdtm_perms_init(void);
>>>    void lkdtm_WRITE_RO(void);
>>>    void lkdtm_WRITE_RO_AFTER_INIT(void);
>>> +void lkdtm_WRITE_RO_PMALLOC(void);
>> Does this need some sort of #ifdef too?
> Not strictly. It's just a function declaration.
> As long as it is not used, the linker will not complain.
> The #ifdef placed around the use and definition is sufficient, from a
> correctness perspective.
>
> But it's a different question if there is any standard in linux about
> hiding also the declaration.


I'd prefer hiding it if it's contents are being ifdef'ed out, but I 
really think it's more of a maintainer preference question.


>
> I am not very fond of #ifdefs, so when I can I try to avoid them.
>
>