check for active_console before using it

Other vga_hw_* functions do the same.
Fixes a segmentation fault.  Trigger: boot with -nodefaults,
then connect via vnc.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/console.c b/console.c
index 7070b1b..4c42b28 100644 (file)
--- a/console.c
+++ b/console.c
@@ -167,7 +167,7 @@ void vga_hw_update(void)
 
 void vga_hw_invalidate(void)
 {
-    if (active_console->hw_invalidate)
+    if (active_console && active_console->hw_invalidate)
         active_console->hw_invalidate(active_console->hw);
 }