fbdev: au1200fb: Fix potential divide by zero

[ Upstream commit 44a3b36b42acfc433aaaf526191dd12fbb919fdb ]

var->pixclock can be assigned to zero by user. Without
proper check, divide by zero would occur when invoking
macro PICOS2KHZ in au1200fb_fb_check_var.

Error out if var->pixclock is zero.

Signed-off-by: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/video/fbdev/au1200fb.c b/drivers/video/fbdev/au1200fb.c
index 265d3b45efd0c0d7ef8e5f50f005f892f4d95ef5..43a4dddaafd52d1861b7dd2295edfa2909c116f5 100644 (file)
--- a/drivers/video/fbdev/au1200fb.c
+++ b/drivers/video/fbdev/au1200fb.c
@@ -1040,6 +1040,9 @@ static int au1200fb_fb_check_var(struct fb_var_screeninfo *var,
        u32 pixclock;
        int screen_size, plane;
 
+       if (!var->pixclock)
+               return -EINVAL;
+
        plane = fbdev->plane;
 
        /* Make sure that the mode respect all LCD controller and