fix - ensure we don't use bootconsoles after init has been released

Gerd Hoffmann pointed out that my patch from yesterday can lead
to a null pointer dereference if the kernel is booted with no
console, and no earlyprintk defined. This fixes that issue.

Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index 5c7c325b29cc..8451dfc31d25 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1085,10 +1085,12 @@ EXPORT_SYMBOL(unregister_console);
 
 static int __init disable_boot_consoles(void)
 {
-        if (console_drivers->flags & CON_BOOT) {
-                printk(KERN_INFO "turn off boot console %s%d\n",
-                        console_drivers->name, console_drivers->index);
-                return unregister_console(console_drivers);
+        if (console_drivers != NULL) {
+                if (console_drivers->flags & CON_BOOT) {
+                        printk(KERN_INFO "turn off boot console %s%d\n",
+                                console_drivers->name, console_drivers->index);
+                        return unregister_console(console_drivers);
+                }
         }
         return 0;
 }