linux-kernel - Re: [PATCH] linux/container

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <c750428f-cbeb-53f5-5865-fa0af263b15e@kernel.org>
Date:   Mon, 21 Aug 2023 13:23:41 +0200
From:   Alejandro Colomar <alx@...nel.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     qat-linux@...el.com, Alejandro Colomar <alx.manpages@...il.com>,
        linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Lucas Segarra Fernandez <lucas.segarra.fernandez@...el.com>,
        Giovanni Cabiddu <giovanni.cabiddu@...el.com>
Subject: Re: [PATCH] linux/container_of.h: Add memberof()

Hi Andy,

On 2023-08-21 13:18, Andy Shevchenko wrote:
> On Sun, Aug 20, 2023 at 09:52:22PM +0200, Alejandro Colomar wrote:
>>  
>> -#define typeof_member(T, m)	typeof(((T*)0)->m)
>> +
>> +#define memberof(T, member)  ((T){}.member)
> 
> I'm not sure. This seems to me utilization of compound literal, while above
> uses direct struct member pointer calculations.

Both can be used in most cases.  The only exception is offsetof(3), where
you need the pointer calculation.  The good thing about the compound
literal is that it's farther away from causing UB, but if that's not a
concern --using sizeof() or typeof() will usually make things safe from
UB, as there's really no dereference, but just to be a little paranoic--,
I could change the definition of memberof() to use the pointer thing.

Should I send a v2 with the pointer thing?

[I'll take some time, as I need to restore my USB with keys, which just
died yesterday.  I didn't sign this email due to that.]

Cheers,
Alex

> 
>> +#define typeof_member(T, m)  typeof(memberof(T, m))
> 

-- 
<http://www.alejandro-colomar.es/>
GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5