console: Fix segfault on screendump without VGA adapter

When trying to create a screen dump without having any VGA adapter
inside the guest, QEMU segfaults.

This is because it's trying to switch back to the "previous" screen
it was on before dumping the VGA screen. Unfortunately, in my case
there simply is no previous screen so it accesses a NULL pointer.

Fix it by checking if previous_active_console is actually available.

This is 1.0 material.

Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/console.c b/console.c
index f6fe44195be825e0e60a3ebff8df7e02d5890871..ed6a653fdfc553135ff59d68881457165c0298d7 100644 (file)
--- a/console.c
+++ b/console.c
@@ -186,7 +186,9 @@ void vga_hw_screen_dump(const char *filename)
         consoles[0]->hw_screen_dump(consoles[0]->hw, filename);
     }
 
-    console_select(previous_active_console->index);
+    if (previous_active_console) {
+        console_select(previous_active_console->index);
+    }
 }
 
 void vga_hw_text_update(console_ch_t *chardata)