video: fbdev: pxa3xx-gcu: Fix integer overflow in pxa3xx_gcu_write

[ Upstream commit a09d2d00af53b43c6f11e6ab3cb58443c2cac8a7 ]

In pxa3xx_gcu_write, a count parameter of type size_t is passed to words of
type int.  Then, copy_from_user() may cause a heap overflow because it is used
as the third argument of copy_from_user().

Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/video/fbdev/pxa3xx-gcu.c b/drivers/video/fbdev/pxa3xx-gcu.c
index 184773b6b9e4f254ab360e55e6a253d395b981c0..2cca4b763d8dc61ebfa9c631800fe13b768e5e8b 100644 (file)
--- a/drivers/video/fbdev/pxa3xx-gcu.c
+++ b/drivers/video/fbdev/pxa3xx-gcu.c
@@ -391,7 +391,7 @@ pxa3xx_gcu_write(struct file *file, const char *buff,
        struct pxa3xx_gcu_batch *buffer;
        struct pxa3xx_gcu_priv *priv = to_pxa3xx_gcu_priv(file);
 
-       int words = count / 4;
+       size_t words = count / 4;
 
        /* Does not need to be atomic. There's a lock in user space,
         * but anyhow, this is just for statistics. */