UPSTREAM: video: fbdev: pxa3xx-gcu: Fix integer overflow in pxa3xx_gc…

…u_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().

Bug: 245928838
Signed-off-by: Hyunwoo Kim <[email protected]>
Signed-off-by: Helge Deller <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Lee Jones <[email protected]>
Change-Id: I9e21917a52e2cb78cc640a77a6eba21838aa8655

drivers/video/fbdev/pxa3xx-gcu.c

@@ -381,7 +381,7 @@ 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. */