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 fbeeed5afe350deff19eea67c1463ba5ba158fe6..aa502b3ba25aeb7187921b4a4a4b408a701515ac 100644 (file)
--- 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;