[PATCH] Fix crash in unregister_console()

If unregister_console() is inadvertently called while no consoles are
registered, it will crash trying to dereference NULL pointer.  It is
necessary to fix that because register_console() provides no indication
that it actually registered the console passed in.  In fact, it may well
decide not to register it based on various things...

(akpm: It'd be better to make register_console() return something and fix the
callers.  All 106 of them...)

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/printk.c b/kernel/printk.c
index ac8a08f3620786f266374d321312629c73e6ac01..5287be83e3e7951740bfe4350dbc763f8d663981 100644 (file)
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -956,7 +956,7 @@ int unregister_console(struct console *console)
        if (console_drivers == console) {
                console_drivers=console->next;
                res = 0;
-       } else {
+       } else if (console_drivers) {
                for (a=console_drivers->next, b=console_drivers ;
                     a; b=a, a=b->next) {
                        if (a == console) {