releases/3.4.4/drm-via-initialize-object_idr.patch

From ce020ea53264f1460ae619cfc12f968dbd0b8974 Mon Sep 17 00:00:00 2001
From: Márton Németh <nm127@freemail.hu>
Date: Sun, 10 Jun 2012 23:39:55 +0200
Subject: drm via: initialize object_idr
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From: Márton Németh <nm127@freemail.hu>

commit ce020ea53264f1460ae619cfc12f968dbd0b8974 upstream.

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>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/via/via_map.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- 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 *d
 	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);