linux-kernel - Re: [PATCH] misc: vexpress: Replace zero-length array with flexible-array member

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Date:   Thu, 20 Feb 2020 17:16:21 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Liviu Dudau <liviu.dudau@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] misc: vexpress: Replace zero-length array with
 flexible-array member

On Tue, Feb 11, 2020 at 03:10:10PM -0600, Gustavo A. R. Silva wrote:
> The current codebase makes use of the zero-length array language
> extension to the C90 standard, but the preferred mechanism to declare
> variable-length types such as these ones is a flexible array member[1][2],
> introduced in C99:
> 
> struct foo {
>         int stuff;
>         struct boo array[];
> };
> 
> By making use of the mechanism above, we will get a compiler warning
> in case the flexible array does not occur last in the structure, which
> will help us prevent some kind of undefined behavior bugs from being
> inadvertenly introduced[3] to the codebase from now on.
> 
> This issue was found with the help of Coccinelle.
> 
> [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> [2] https://github.com/KSPP/linux/issues/21
> [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
> 

Applied for v5.7

--
Regards,
Sudeep