fbdev: nvidia: Fix potential divide by zero

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>

diff --git a/drivers/video/fbdev/nvidia/nvidia.c b/drivers/video/fbdev/nvidia/nvidia.c
index e60a276b4855dcddd06a6ffbe46220b161bba7d5..ea4ba3dfb96bb51d149c0e288286269bc1a1ad0f 100644 (file)
--- a/drivers/video/fbdev/nvidia/nvidia.c
+++ b/drivers/video/fbdev/nvidia/nvidia.c
@@ -764,6 +764,8 @@ 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;