linux-kernel - Re: [PATCH 1/2] drm: make drm_dev_set

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Date:	Tue, 8 Dec 2015 23:28:27 +0000
From:	Emil Velikov <emil.l.velikov@...il.com>
To:	Nicolas Iooss <nicolas.iooss_linux@....org>
Cc:	Boris Brezillon <boris.brezillon@...e-electrons.com>,
	David Airlie <airlied@...ux.ie>,
	Jianwei Wang <jianwei.wang.chn@...il.com>,
	Alison Wang <alison.wang@...escale.com>,
	Mark Yao <mark.yao@...k-chips.com>,
	Thierry Reding <thierry.reding@...il.com>,
	Terje Bergström <tbergstrom@...dia.com>,
	Stephen Warren <swarren@...dotorg.org>,
	ML dri-devel <dri-devel@...ts.freedesktop.org>,
	linux-tegra@...r.kernel.org,
	"Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] drm: make drm_dev_set_unique() not use a format string

On 8 December 2015 at 22:12, Nicolas Iooss <nicolas.iooss_linux@....org> wrote:
> drm_dev_set_unique() uses a format string to define the unique name of a
> device.  This feature is not used as currently all the calls to this
> function either use "%s" as a format string or directly use
> dev_name().
>
> Even though this second kind of call does not introduce security
> problems, because there cannot be "%" characters in dev_name() results,
> gcc issues a warning when building with -Wformat-security flag
> ("warning: format string is not a string literal (potentially
> insecure)").  This warning is useful to find real bugs like the one
> fixed by commit 3958b79266b1 ("configfs: fix kernel infoleak through
> user-controlled format string").  False positives which do not bring
> an extra value make the work of finding real bugs harder.
>
> Therefore remove the format-string feature from drm_dev_set_unique().
>
> Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@....org>
> ---
>  drivers/gpu/drm/drm_drv.c                   | 11 +++--------
>  drivers/gpu/drm/nouveau/nouveau_drm.c       |  2 +-
>  drivers/gpu/drm/rockchip/rockchip_drm_drv.c |  2 +-
>  include/drm/drmP.h                          |  2 +-
>  4 files changed, 6 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 7dd6728dd092..20eaa0aae205 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -797,7 +797,7 @@ EXPORT_SYMBOL(drm_dev_unregister);
>  /**
>   * drm_dev_set_unique - Set the unique name of a DRM device
>   * @dev: device of which to set the unique name
> - * @fmt: format string for unique name
> + * @name: unique name
>   *
>   * Sets the unique name of a DRM device using the specified format string and
>   * a variable list of arguments. Drivers can use this at driver probe time if
You might want to also update the above hunk :-)

-Emil
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