linux-kernel - Re: [PATCH] USB: serial: ti_usb_3410_5052: Replace zero-length array with flexible-array member

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Date:   Wed, 12 Feb 2020 13:04:09 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Johan Hovold <johan@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] USB: serial: ti_usb_3410_5052: Replace zero-length array
 with flexible-array member



On 2/12/20 01:59, Johan Hovold wrote:
> On Tue, Feb 11, 2020 at 05:24:20PM -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.
> 
> Same here, the scripts may need to be updated as you missed a couple of
> instances:
> 
> 	$ git grep '\[0\];' drivers/usb/serial
> 	...
> 	drivers/usb/serial/io_usbvend.h:        __u8    Data[0];                // Data starts here
> 	drivers/usb/serial/io_usbvend.h:        __u8    Data[0];                // Download starts here
> 	...
> 
> Could you replace these as well so that is done in one patch per
> subsystem?
> 

Sure thing. I'll do that.

Thanks for the feedback.
--
Gustavo