linux-kernel - Re: [PATCH] net: stmmac: Avoid VLA usage

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Message-ID: <4c209618-8da0-ef1d-ff79-5da3f235b9bc@synopsys.com>
Date:   Wed, 2 May 2018 15:07:43 +0100
From:   Jose Abreu <Jose.Abreu@...opsys.com>
To:     Kees Cook <keescook@...omium.org>,
        Jose Abreu <Jose.Abreu@...opsys.com>
CC:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        LKML <linux-kernel@...r.kernel.org>,
        "Network Development" <netdev@...r.kernel.org>
Subject: Re: [PATCH] net: stmmac: Avoid VLA usage



On 02-05-2018 13:36, Kees Cook wrote:
> On Wed, May 2, 2018 at 1:54 AM, Jose Abreu <Jose.Abreu@...opsys.com> wrote:
>> Hi Kees,
>>
>> On 01-05-2018 22:01, Kees Cook wrote:
>>> In the quest to remove all stack VLAs from the kernel[1], this switches
>>> the "status" stack buffer to use the existing small (8) upper bound on
>>> how many queues can be checked for DMA, and adds a sanity-check just to
>>> make sure it doesn't operate under pathological conditions.
>>>
>>> [1] https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.kernel.org_r_CA-2B55aFzCG-2DzNmZwX4A2FQpadafLfEzK6CC-3DqPXydAacU1RqZWA-40mail.gmail.com&d=DwIBAg&c=DPL6_X_6JkXFx7AXWqB0tg&r=WHDsc6kcWAl4i96Vm5hJ_19IJiuxx_p_Rzo2g-uHDKw&m=TBD6a7UY2VbpPmV9LOW_eHAyg8uPq1ZPDhq93VROTVE&s=4fvOST1HhWmZ4lThQe-dHCJYEXNOwey00BCXOWm8tKo&e=
>>>
>>> Signed-off-by: Kees Cook <keescook@...omium.org>
>>>
>> I rather prefer the variables declaration in reverse-tree order,
>> but thats just a minor pick.
> I can explicitly reorder the other variables, if you want?

No need by me, unless Giuseppe or Alexandre prefer that. Thanks!

Best Regards,
Jose Miguel Abreu

>
>> Reviewed-by: Jose Abreu <joabreu@...opsys.com>
> Thanks!
>
>> PS: Is VLA warning switch in gcc already active? Because I didn't
>> see this warning in my builds.
> It is not. A bunch of people have been building with KCFLAGS=-Wvla to
> find the VLAs and sending patches. Once we get rid of them all, we can
> add the flag to the top-level Makefile.
>
> -Kees
>