[PATCH AUTOSEL 4.14 7/9] fbdev: intelfb: Fix potential divide by zero

Sasha Levin
2023-03-22T20:12:09Z

[ Upstream commit d823685486a3446d061fed7c7d2f80af984f119a ]

Variable var->pixclock is controlled by user and can be assigned
to zero. Without proper check, divide by zero would occur in
intelfbhw_validate_mode and intelfbhw_mode_to_hw.

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>
---
drivers/video/fbdev/intelfb/intelfbdrv.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/intelfb/intelfbdrv.c b/drivers/video/fbdev/intelfb/intelfbdrv.c
index d7463a2a5d83f..c97c0c8514809 100644
--- a/drivers/video/fbdev/intelfb/intelfbdrv.c
+++ b/drivers/video/fbdev/intelfb/intelfbdrv.c
@@ -1215,6 +1215,9 @@ static int intelfb_check_var(struct fb_var_screeninfo *var,

dinfo = GET_DINFO(info);

+ if (!var->pixclock)
+ return -EINVAL;
+
/* update the pitch */
if (intelfbhw_validate_mode(dinfo, var) != 0)
return -EINVAL;
--
2.39.2