linux-kernel - Re: [PATCH v2 4/5] staging: r8188eu: restricted _

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:   Sat, 21 Aug 2021 19:48:46 +0530
From:   Aakash Hemadri <aakashhemadri123@...il.com>
To:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Larry Finger <Larry.Finger@...inger.net>,
        Phillip Potter <phil@...lpotter.co.uk>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/5] staging: r8188eu: restricted __be16 degrades to
 int

On 21/08/20 05:10PM, Fabio M. De Francesco wrote:
> Building on the objections you had from Greg I suggest that, before attempting 
> anew to address problems like these, you get a better understanding of the topics of 
> native and network endianness and of the API that (conditionally) swap bytes 
> in a variable between little endian and big endian representation.
> 
> To start with, please note that the following code leads to tests for "v.vub[0] == 0xDD" 
> which is true on little endian architectures while "v.vub[0] == 0xAA" is true on big 
> endian ones...
> 
> union {
>         u32 vud;
>         u8 vub[4];
> } v;
> 
> v.vud = 0xAABBCCDD;
> 
> Also note that API like cpu_to_be32(), htonl(), be32_to_cpu(), ntohl, and the likes are 
> used to (conditionally) swap bytes (i.e., change the arrangement of the bytes in a 
> multi-bytes variable).
> 
> Casts have very different purposes and usage patterns and, above all, they cannot 
> magically change the endianness of a variable.
> 
> Regards,
> 
> Fabio
> 

Thanks for the explanation Fabio!
Will rework and send it through!

Thanks,
Aakash Hemadri