[14/25] drm/i915: Rephrase pwrite bounds checking to avoid any potential overflow

[Greg KH <gregkh@suse.de>]

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

------------------
Content-Length: 1407
Lines: 47

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

commit 7dcd2499deab8f10011713c40bc2f309c9b65077 upstream

... and do the same for pread.

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 |   16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -482,12 +482,8 @@ i915_gem_pread_ioctl(struct drm_device *
 		return -EBADF;
 	obj_priv = obj->driver_private;
 
-	/* Bounds check source.
-	 *
-	 * XXX: This could use review for overflow issues...
-	 */
-	if (args->offset > obj->size || args->size > obj->size ||
-	    args->offset + args->size > obj->size) {
+	/* Bounds check source.  */
+	if (args->offset > obj->size || args->size > obj->size - args->offset) {
 		ret = -EINVAL;
 		goto err;
 	}
@@ -960,12 +956,8 @@ i915_gem_pwrite_ioctl(struct drm_device
 		return -EBADF;
 	obj_priv = obj->driver_private;
 
-	/* Bounds check destination.
-	 *
-	 * XXX: This could use review for overflow issues...
-	 */
-	if (args->offset > obj->size || args->size > obj->size ||
-	    args->offset + args->size > obj->size) {
+	/* Bounds check destination. */
+	if (args->offset > obj->size || args->size > obj->size - args->offset) {
 		ret = -EINVAL;
 		goto err;
 	}