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

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Message-Id: <20250323185737.602339-1-listdansp@mail.ru>
Date: Sun, 23 Mar 2025 18:57:37 +0000
From: Danila Chernetsov <listdansp@...l.ru>
To: Helge Deller <deller@....de>
Cc: Danila Chernetsov <listdansp@...l.ru>,
	linux-fbdev@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org
Subject: [PATCH] video: fbdev: kyro: Add some geometry checks.

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@...l.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