From: Wei Chen <harperchen1110@gmail.com>
Date: Wed, 15 Mar 2023 07:18:31 +0000 (+0000)
Subject: fbdev: nvidia: Fix potential divide by zero
X-Git-Tag: v5.4.240~38
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=868f247e47ef1346b706d17cbd104b367f60823b;p=thirdparty%2Fkernel%2Fstable.git

fbdev: nvidia: Fix potential divide by zero

[ Upstream commit 92e2a00f2987483e1f9253625828622edd442e61 ]

variable var->pixclock can be set by user. In case it
equals to zero, divide by zero would occur in nvidiafb_set_par.

Similar crashes have happened in other fbdev drivers. There
is no check and modification on var->pixclock along the call
chain to nvidia_check_var and nvidiafb_set_par. We believe it
could also be triggered in driver nvidia from user site.

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/nvidia/nvidia.c b/drivers/video/fbdev/nvidia/nvidia.c
index fbeeed5afe350..aa502b3ba25ae 100644
--- a/drivers/video/fbdev/nvidia/nvidia.c
+++ b/drivers/video/fbdev/nvidia/nvidia.c
@@ -766,6 +766,8 @@ static int nvidiafb_check_var(struct fb_var_screeninfo *var,
 	int pitch, err = 0;
 
 	NVTRACE_ENTER();
+	if (!var->pixclock)
+		return -EINVAL;
 
 	var->transp.offset = 0;
 	var->transp.length = 0;