The overlay viewport end coordinates are computed from the viewport
origin and dimensions using 32-bit unsigned arithmetic. Large input
values can cause these calculations to wrap around before the resulting
coordinates are passed to SetOverlayViewPort().
SetOverlayViewPort() packs the viewport coordinates into 16-bit
register fields. The X coordinates are additionally adjusted by +2
and +1 before being written. Validate the coordinate calculations
for 32-bit wraparound and ensure that the adjusted coordinates fit
within their 16-bit register fields before calling
SetOverlayViewPort().
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Danila Chernetsov <[email protected]>
---
drivers/video/fbdev/kyro/fbdev.c | 24 +++++++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/drivers/video/fbdev/kyro/fbdev.c b/drivers/video/fbdev/kyro/fbdev.c
index d756b3603fa6..133c91716c49 100644
--- a/drivers/video/fbdev/kyro/fbdev.c
+++ b/drivers/video/fbdev/kyro/fbdev.c
@@ -369,6 +369,9 @@ static int kyro_dev_overlay_create(u32 ulWidth,
static int kyro_dev_overlay_viewport_set(u32 x, u32 y, u32 ulWidth, u32
ulHeight)
{
+ u32 right;
+ u32 bottom;
+
if (deviceInfo.ulOverlayOffset == 0)
/* probably haven't called CreateOverlay yet */
return -EINVAL;
@@ -378,11 +381,30 @@ static int kyro_dev_overlay_viewport_set(u32 x, u32 y,
u32 ulWidth, u32 ulHeight
(x < 2 && ulWidth + 2 == 0))
return -EINVAL;
+ /*
+ * SetOverlayViewPort() adjusts X coordinates by +2 (left) and +1
+ * (right) before packing them into 16-bit register fields.
+ */
+ if (x > U16_MAX - 2 || y > U16_MAX)
+ return -EINVAL;
+
+ right = x + ulWidth;
+ bottom = y + ulHeight;
+
+ if (right < x || bottom < y)
+ return -EINVAL;
+
+ right--;
+ bottom--;
+
+ if (right > U16_MAX - 1 || bottom > U16_MAX)
+ return -EINVAL;
+
/* Stop Ramdac Output */
DisableRamdacOutput(deviceInfo.pSTGReg);
SetOverlayViewPort(deviceInfo.pSTGReg,
- x, y, x + ulWidth - 1, y + ulHeight - 1);
+ x, y, right, bottom);
EnableOverlayPlane(deviceInfo.pSTGReg);
/* Start Ramdac Output */
--
2.25.1
