Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <54fe1ebc-6b3a-178c-d7d2-fb5486f54e8d@embeddedor.com>
Date:   Fri, 23 Jun 2023 08:14:34 -0600
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.11.0
Subject: Re: [PATCH][next] MIPS: dec: prom: Address -Warray-bounds warning
Content-Language: en-US
To:     "Maciej W. Rozycki" <macro@orcam.me.uk>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc:     "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-hardening@vger.kernel.org
References: <ZJTcvfpvhvF+OLjc@work> <20230623131019.GD11636@alpha.franken.de>
 <alpine.DEB.2.21.2306231432120.14084@angie.orcam.me.uk>
From:   "Gustavo A. R. Silva" <gustavo@embeddedor.com>
In-Reply-To: <alpine.DEB.2.21.2306231432120.14084@angie.orcam.me.uk>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk


On 6/23/23 07:41, Maciej W. Rozycki wrote:
> On Fri, 23 Jun 2023, Thomas Bogendoerfer wrote:
> 
>>> Zero-length arrays are deprecated, and we are replacing them with flexible
>>> array members instead. So, replace zero-length array with flexible-array
>>> member in struct memmap.
> 
>   Technically it is a semantics bug fix actually, as the TURBOchannel
> firmware specification (from Jan 1993) says it's:
> 
> typedef struct{ int pagesize; unsigned char bitmap[];}memmap;
> int getbitmap(memmap *map);
> 
> (formatting preserved as in the document) so it should have always been a
> flexible array member.  Maybe old (2.x) GCC versions had an issue with it
> or something, as otherwise I can't imagine why whoever added our typedef
> did it differently from the spec.

Apparently, flexible-array members were supported in some 2.x versions as an
extension to the language; and it was not until GCC 3.0 that they were fully
supported by the compiler.

> 
>> applied to mips-next.
> 
>   Not sure if you can retrofit it, but:
> 
> Acked-by: Maciej W. Rozycki <macro@orcam.me.uk>

Thanks!
--
Gustavo