[PATCH] drm via: initialize object_idr

[PATCH] drm via: initialize object_idr

[Németh Márton]

From: Márton Németh <nm127@freemail.hu>

The field obejct_idr of struct drm_via_private was introduced with the
commit http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=77ee8f3825054f23b17e9c8f728f061defd86cdc .
In that patch idr_init(&dev->object_name_idr) was called instead of
idr_init(&dev_priv->object_idr) by mistake, leaving the dev_priv->object_idr
uninitialized. To be more exact, the object_idr buffer is filled with zeros
because of kzalloc(), but the dev_priv->object_idr.lock spinlock can cause
system freeze at lib/idr.c:move_to_free_list() when spin_lock_irqsave()
is called on this spinlock.

The patch was tested on Clevo D4J, model D410J laptop, on the following
hardware, without AGP kernel module loaded:

  # lspci -s 01:00.0 -n
  01:00.0 0300: 1106:3108 (rev 01)
  # lspci -s 01:00.0 -v
  01:00.0 VGA compatible controller: VIA Technologies, Inc. K8M800/K8N800/K8N800A [S3 UniChrome Pro] (rev 01) (prog-if 00 [VGA controller])
          Subsystem: CLEVO/KAPOK Computer Device 4702
          Flags: bus master, 66MHz, medium devsel, latency 64, IRQ 16
          Memory at f0000000 (32-bit, prefetchable) [size=64M]
          Memory at d1000000 (32-bit, non-prefetchable) [size=16M]
          Expansion ROM at <unassigned> [disabled]
          Capabilities: [60] Power Management version 2
          Capabilities: [70] AGP version 3.0

Signed-off-by: Márton Németh <nm127@freemail.hu>
---
diff --git a/drivers/gpu/drm/via/via_map.c b/drivers/gpu/drm/via/via_map.c
index 1f18225..c126182 100644
--- a/drivers/gpu/drm/via/via_map.c
+++ b/drivers/gpu/drm/via/via_map.c
@@ -100,12 +100,11 @@ int via_driver_load(struct drm_device *dev, unsigned long chipset)
 	if (dev_priv == NULL)
 		return -ENOMEM;

+	idr_init(&dev_priv->object_idr);
 	dev->dev_private = (void *)dev_priv;

 	dev_priv->chipset = chipset;

-	idr_init(&dev->object_name_idr);
-
 	pci_set_master(dev->pdev);

 	ret = drm_vblank_init(dev, 1);

Re: [PATCH] drm via: initialize object_idr

[Daniel Vetter]

On Sun, Jun 10, 2012 at 11:39:55PM +0200, Németh Márton wrote:
> From: Márton Németh <nm127@freemail.hu>
> 
> The field obejct_idr of struct drm_via_private was introduced with the
> commit http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=77ee8f3825054f23b17e9c8f728f061defd86cdc .
> In that patch idr_init(&dev->object_name_idr) was called instead of
> idr_init(&dev_priv->object_idr) by mistake, leaving the dev_priv->object_idr
> uninitialized. To be more exact, the object_idr buffer is filled with zeros
> because of kzalloc(), but the dev_priv->object_idr.lock spinlock can cause
> system freeze at lib/idr.c:move_to_free_list() when spin_lock_irqsave()
> is called on this spinlock.
> 
> The patch was tested on Clevo D4J, model D410J laptop, on the following
> hardware, without AGP kernel module loaded:
> 
>   # lspci -s 01:00.0 -n
>   01:00.0 0300: 1106:3108 (rev 01)
>   # lspci -s 01:00.0 -v
>   01:00.0 VGA compatible controller: VIA Technologies, Inc. K8M800/K8N800/K8N800A [S3 UniChrome Pro] (rev 01) (prog-if 00 [VGA controller])
>           Subsystem: CLEVO/KAPOK Computer Device 4702
>           Flags: bus master, 66MHz, medium devsel, latency 64, IRQ 16
>           Memory at f0000000 (32-bit, prefetchable) [size=64M]
>           Memory at d1000000 (32-bit, non-prefetchable) [size=16M]
>           Expansion ROM at <unassigned> [disabled]
>           Capabilities: [60] Power Management version 2
>           Capabilities: [70] AGP version 3.0
> 
> Signed-off-by: Márton Németh <nm127@freemail.hu>

Meh, I fail, thanks for catching this. Although the drm/sis driver has the
same problem, care to write that patch, too? In any case:

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org

-Daniel

> ---
> diff --git a/drivers/gpu/drm/via/via_map.c b/drivers/gpu/drm/via/via_map.c
> index 1f18225..c126182 100644
> --- a/drivers/gpu/drm/via/via_map.c
> +++ b/drivers/gpu/drm/via/via_map.c
> @@ -100,12 +100,11 @@ int via_driver_load(struct drm_device *dev, unsigned long chipset)
>  	if (dev_priv == NULL)
>  		return -ENOMEM;
> 
> +	idr_init(&dev_priv->object_idr);
>  	dev->dev_private = (void *)dev_priv;
> 
>  	dev_priv->chipset = chipset;
> 
> -	idr_init(&dev->object_name_idr);
> -
>  	pci_set_master(dev->pdev);
> 
>  	ret = drm_vblank_init(dev, 1);

-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48

[PATCH] drm sis: initialize object_idr

[Németh Márton]

From: Márton Németh <nm127@freemail.hu>

The filed object_idr of struct drm_sis_private was introduced with
commit http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=6de8a748881f1cd9d795454da2b6db616d5ca3d7 .

The idr_init(&dev->object_name_idr) is called instead of
idr_init(&dev_priv->object_idr) by mistake, leaving object_idr
uninitialized. Correct this.

This patch was not tested because of lack of hardware.

Signed-off-by: Márton Németh <nm127@freemail.hu>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
---
diff --git a/drivers/gpu/drm/sis/sis_drv.c b/drivers/gpu/drm/sis/sis_drv.c
index 30d98d1..dd14cd1 100644
--- a/drivers/gpu/drm/sis/sis_drv.c
+++ b/drivers/gpu/drm/sis/sis_drv.c
@@ -47,9 +47,9 @@ static int sis_driver_load(struct drm_device *dev, unsigned long chipset)
 	if (dev_priv == NULL)
 		return -ENOMEM;

+	idr_init(&dev_priv->object_idr);
 	dev->dev_private = (void *)dev_priv;
 	dev_priv->chipset = chipset;
-	idr_init(&dev->object_name_idr);

 	return 0;
 }