Re: [PATCH v2 1/2] drm: Make HW_LOCK access functions optional.

From: Daniel Vetter <daniel@ffwll.ch>
To: Peter Antoine <peter.antoine@intel.com>
Cc: daniel.vetter@ffwll.ch, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH v2 1/2] drm: Make HW_LOCK access functions optional.
Date: Wed, 13 May 2015 09:14:29 +0200	[thread overview]
Message-ID: <20150513071429.GR15256@phenom.ffwll.local> (raw)
In-Reply-To: <1431500088-15278-2-git-send-email-peter.antoine@intel.com>

On Wed, May 13, 2015 at 07:54:47AM +0100, Peter Antoine wrote:
> As these functions are only used by one driver and there are security holes
> in these functions. Make the functions optional.

Is there a reference for why nouveau needs hw locks too? Also have you
done an audit of mesa history and X history to make sure there's no other
driver accidentally using it with a modern kms driver?

> Issue: VIZ-5485
> Signed-off-by: Peter Antoine <peter.antoine@intel.com>
> ---
>  drivers/gpu/drm/drm_lock.c            |  6 ++++++
>  drivers/gpu/drm/nouveau/nouveau_drm.c |  3 ++-
>  include/drm/drmP.h                    | 23 ++++++++++++-----------
>  3 files changed, 20 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_lock.c b/drivers/gpu/drm/drm_lock.c
> index f861361..21eb180 100644
> --- a/drivers/gpu/drm/drm_lock.c
> +++ b/drivers/gpu/drm/drm_lock.c
> @@ -61,6 +61,9 @@ int drm_legacy_lock(struct drm_device *dev, void *data,
>  	struct drm_master *master = file_priv->master;
>  	int ret = 0;
>  
> +	if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))

You also need to allow these for all legacy drivers, i.e. without
DRIVER_MODESET.
-Daniel

> +		return -EINVAL;
> +
>  	++file_priv->lock_count;
>  
>  	if (lock->context == DRM_KERNEL_CONTEXT) {
> @@ -153,6 +156,9 @@ int drm_legacy_unlock(struct drm_device *dev, void *data, struct drm_file *file_
>  	struct drm_lock *lock = data;
>  	struct drm_master *master = file_priv->master;
>  
> +	if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
> +		return -EINVAL;
> +
>  	if (lock->context == DRM_KERNEL_CONTEXT) {
>  		DRM_ERROR("Process %d using kernel context %d\n",
>  			  task_pid_nr(current), lock->context);
> diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
> index 8904933..9624b38 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_drm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
> @@ -941,7 +941,8 @@ static struct drm_driver
>  driver_stub = {
>  	.driver_features =
>  		DRIVER_USE_AGP |
> -		DRIVER_GEM | DRIVER_MODESET | DRIVER_PRIME | DRIVER_RENDER,
> +		DRIVER_GEM | DRIVER_MODESET | DRIVER_PRIME | DRIVER_RENDER |
> +		DRIVER_KMS_LEGACY_CONTEXT,
>  
>  	.load = nouveau_drm_load,
>  	.unload = nouveau_drm_unload,
> diff --git a/include/drm/drmP.h b/include/drm/drmP.h
> index df6d997..3874942 100644
> --- a/include/drm/drmP.h
> +++ b/include/drm/drmP.h
> @@ -137,17 +137,18 @@ void drm_err(const char *format, ...);
>  /*@{*/
>  
>  /* driver capabilities and requirements mask */
> -#define DRIVER_USE_AGP     0x1
> -#define DRIVER_PCI_DMA     0x8
> -#define DRIVER_SG          0x10
> -#define DRIVER_HAVE_DMA    0x20
> -#define DRIVER_HAVE_IRQ    0x40
> -#define DRIVER_IRQ_SHARED  0x80
> -#define DRIVER_GEM         0x1000
> -#define DRIVER_MODESET     0x2000
> -#define DRIVER_PRIME       0x4000
> -#define DRIVER_RENDER      0x8000
> -#define DRIVER_ATOMIC      0x10000
> +#define DRIVER_USE_AGP			0x1
> +#define DRIVER_PCI_DMA			0x8
> +#define DRIVER_SG			0x10
> +#define DRIVER_HAVE_DMA			0x20
> +#define DRIVER_HAVE_IRQ			0x40
> +#define DRIVER_IRQ_SHARED		0x80
> +#define DRIVER_GEM			0x1000
> +#define DRIVER_MODESET			0x2000
> +#define DRIVER_PRIME			0x4000
> +#define DRIVER_RENDER			0x8000
> +#define DRIVER_ATOMIC			0x10000
> +#define DRIVER_KMS_LEGACY_CONTEXT	0x20000
>  
>  /***********************************************************************/
>  /** \name Macros to make printk easier */
> -- 
> 1.9.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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