linux-kernel - Re: [PATCH v2] rtc: remove VLA usage

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Date:   Thu, 8 Mar 2018 10:49:19 +0100
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     "Gustavo A. R. Silva" <garsilva@...eddedor.com>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] rtc: remove VLA usage

On 07/03/2018 at 20:27:56 -0600, Gustavo A. R. Silva wrote:
> In preparation to enabling -Wvla, remove VLA and replace it
> with a fixed-length array instead.
> 
> From a security viewpoint, the use of Variable Length Arrays can be
> a vector for stack overflow attacks. Also, in general, as the code
> evolves it is easy to lose track of how big a VLA can get. Thus, we
> can end up having segfaults that are hard to debug.
> 
> Also, fixed as part of the directive to remove all VLAs from
> the kernel: https://lkml.org/lkml/2018/3/7/621
> 

That is a good description, thanks

> Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
> ---
> Changes in v2:
>  - Update changelog as per Alexandre Belloni request.
>  - Update the code for rtc-bq32k driver based on Alexandre's feedback.
> 
>  drivers/rtc/rtc-bq32k.c  | 6 +++++-
>  drivers/rtc/rtc-mcp795.c | 2 +-
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
Applied.

-- 
Alexandre Belloni, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com