fbdev: kyro: Validate overlay viewport coordinates

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 <listdansp@mail.ru>
Signed-off-by: Helge Deller <deller@gmx.de>

0 files changed, 0 insertions, 0 deletions