[PATCH] video: fbdev: kyro: Add some geometry checks.

[Danila Chernetsov]

The check protects against division by 0, integer wraparound,
and overflow Start/End window settings.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Danila Chernetsov <listdansp at mail.ru>
---
 drivers/video/fbdev/kyro/fbdev.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/video/fbdev/kyro/fbdev.c b/drivers/video/fbdev/kyro/fbdev.c
index 08ee8baa79f8..1d5246313d9a 100644
--- a/drivers/video/fbdev/kyro/fbdev.c
+++ b/drivers/video/fbdev/kyro/fbdev.c
@@ -378,6 +378,13 @@ static int kyro_dev_overlay_viewport_set(u32 x, u32 y, u32 ulWidth, u32 ulHeight
 	    (x < 2 && ulWidth + 2 == 0))
 		return -EINVAL;
 
+	/* The check protects against division by 0, integer wraparound,
+	 * and overflow Start/End window settings.
+	 */
+	if (x + ulWidth - 1 <= x || y + ulHeight - 1 <= y ||
+	    x + ulWidth - 1 > 65535 || y + ulHeight - 1 > 65535)
+		return -EINVAL;
+
 	/* Stop Ramdac Output */
 	DisableRamdacOutput(deviceInfo.pSTGReg);
 
-- 
2.25.1