Matt Redfearn 2b1be689f3 printk/console: Always disable boot consoles that use init memory before it is freed ... Commit 4c30c6f566 ("kernel/printk: do not turn off bootconsole in printk_late_init() if keep_bootcon") added a check on keep_bootcon to ensure that boot consoles were kept around until the real console is registered. This can lead to problems if the boot console data and code are in the init section, since it can be freed before the boot console is unregistered. Commit 81cc26f2bd ("printk: only unregister boot consoles when necessary") fixed this a better way. It allowed to keep boot consoles that did not use init data. Unfortunately it did not remove the check of keep_bootcon. This can lead to crashes and weird panics when the bootconsole is accessed after free, especially if page poisoning is in use and the code / data have been overwritten with a poison value. To prevent this, always free the boot console if it is within the init section. In addition, print a warning about that the console is removed prematurely. Finally there is a new comment how to avoid the warning. It replaced an explanation that duplicated a more comprehensive function description few lines above. Fixes: 4c30c6f566 ("kernel/printk: do not turn off bootconsole in printk_late_init() if keep_bootcon") Link: http://lkml.kernel.org/r/1500036673-7122-2-git-send-email-pmladek@suse.com Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jslaby@suse.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: "Fabio M. Di Nitto" <fdinitto@redhat.com> Cc: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com> [pmladek@suse.com: print the warning, code and comments clean up] Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com>		2017-07-27 15:04:21 +02:00
..
braille.c	braille-console: Fix value returned by _braille_console_setup	2017-03-31 15:29:06 +02:00
braille.h	braille-console: Fix value returned by _braille_console_setup	2017-03-31 15:29:06 +02:00
console_cmdline.h	console: Fix console name size mismatch	2015-03-07 03:39:55 +01:00
internal.h	printk: Use the main logbuf in NMI when logbuf_lock is available	2017-05-19 14:42:19 +02:00
Makefile	printk: introduce per-cpu safe_print seq buffer	2017-02-08 11:07:11 +01:00
printk_safe.c	printk: add __printf attributes to internal functions	2017-06-13 16:36:02 +02:00
printk.c	printk/console: Always disable boot consoles that use init memory before it is freed	2017-07-27 15:04:21 +02:00