From ce9d419dbecc292cc3e06e8b1d6d123d3fa813a4 Mon Sep 17 00:00:00 2001

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

Date: Sun, 26 Sep 2010 20:50:05 +0100

Subject: drm/i915: Sanity check pread/pwrite

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: 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

@@ -465,8 +465,15 @@ 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_unlocked(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)) {

@@ -478,8 +485,8 @@ i915_gem_pread_ioctl(struct drm_device *

 							file_priv);

 	}

+err:

 	drm_gem_object_unreference_unlocked(obj);

-

 	return ret;

 }

@@ -568,8 +575,6 @@ 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);

@@ -928,8 +933,15 @@ 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_unlocked(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

@@ -963,8 +975,8 @@ i915_gem_pwrite_ioctl(struct drm_device

 		DRM_INFO("pwrite failed %d\n", ret);

 #endif

+err:

 	drm_gem_object_unreference_unlocked(obj);

-

 	return ret;

 }