linux-kernel - [PATCH 4.5 080/128] drm/vmwgfx: Fix order of operation

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Message-Id: <20160605222323.753909643@linuxfoundation.org>
Date:	Sun,  5 Jun 2016 15:23:55 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Sinclair Yeh <syeh@...are.com>,
	Thomas Hellstrom <thellstrom@...are.com>
Subject: [PATCH 4.5 080/128] drm/vmwgfx: Fix order of operation

4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sinclair Yeh <syeh@...are.com>

commit 7851496a32319237456919575e5f4ba62f74cc7d upstream.

mode->hdisplay * (var->bits_per_pixel + 7) gets evaluated before
the division, potentially making the pitch larger than it should
be.

Since the original intention is to do a div-round-up, just use
the macro instead.

Signed-off-by: Sinclair Yeh <syeh@...are.com>
Reviewed-by: Thomas Hellstrom <thellstrom@...are.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/vmwgfx/vmwgfx_fb.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
@@ -573,9 +573,9 @@ static int vmw_fb_set_par(struct fb_info
 		mode = old_mode;
 		old_mode = NULL;
 	} else if (!vmw_kms_validate_mode_vram(vmw_priv,
-					       mode->hdisplay *
-					       (var->bits_per_pixel + 7) / 8,
-					       mode->vdisplay)) {
+					mode->hdisplay *
+					DIV_ROUND_UP(var->bits_per_pixel, 8),
+					mode->vdisplay)) {
 		drm_mode_destroy(vmw_priv->dev, mode);
 		return -EINVAL;
 	}