releases/2.6.32.49/drm-i915-sanity-check-pread-pwrite.patch

From dan.carpenter@oracle.com  Fri Nov 18 11:32:12 2011
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 15 Nov 2011 09:39:33 +0300
Subject: drm/i915: Sanity check pread/pwrite
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <greg@kroah.com>, Chris Wilson <chris@chris-wilson.co.uk>
Message-ID: <20111115063933.GD30827@elgon.mountain>
Content-Disposition: inline

From: Chris Wilson <chris@chris-wilson.co.uk>

commit ce9d419dbecc292cc3e06e8b1d6d123d3fa813a4 upstream.

Move the access control up from the fast paths, which are no longer
universally taken first, up into the caller. This then duplicates some
sanity checking along the slow paths, but is much simpler.
Tracked as CVE-2010-2962.

Reported-by: Kees Cook <kees@ubuntu.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/gpu/drm/i915/i915_gem.c |   28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -488,8 +488,15 @@ i915_gem_pread_ioctl(struct drm_device *
 	 */
 	if (args->offset > obj->size || args->size > obj->size ||
 	    args->offset + args->size > obj->size) {
-		drm_gem_object_unreference(obj);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto err;
+	}
+
+	if (!access_ok(VERIFY_WRITE,
+		       (char __user *)(uintptr_t)args->data_ptr,
+		       args->size)) {
+		ret = -EFAULT;
+		goto err;
 	}
 
 	if (i915_gem_object_needs_bit17_swizzle(obj)) {
@@ -501,8 +508,8 @@ i915_gem_pread_ioctl(struct drm_device *
 							file_priv);
 	}
 
+err:
 	drm_gem_object_unreference(obj);
-
 	return ret;
 }
 
@@ -592,8 +599,6 @@ i915_gem_gtt_pwrite_fast(struct drm_devi
 
 	user_data = (char __user *) (uintptr_t) args->data_ptr;
 	remain = args->size;
-	if (!access_ok(VERIFY_READ, user_data, remain))
-		return -EFAULT;
 
 
 	mutex_lock(&dev->struct_mutex);
@@ -961,8 +966,15 @@ i915_gem_pwrite_ioctl(struct drm_device
 	 */
 	if (args->offset > obj->size || args->size > obj->size ||
 	    args->offset + args->size > obj->size) {
-		drm_gem_object_unreference(obj);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto err;
+	}
+
+	if (!access_ok(VERIFY_READ,
+		       (char __user *)(uintptr_t)args->data_ptr,
+		       args->size)) {
+		ret = -EFAULT;
+		goto err;
 	}
 
 	/* We can only do the GTT pwrite on untiled buffers, as otherwise
@@ -995,8 +1007,8 @@ i915_gem_pwrite_ioctl(struct drm_device
 		DRM_INFO("pwrite failed %d\n", ret);
 #endif
 
+err:
 	drm_gem_object_unreference(obj);
-
 	return ret;
 }