diff options
| author | Andreas Bießmann <andreas@biessmann.de> | 2013-08-02 12:23:34 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-08-05 15:06:46 +0800 |
| commit | 16cf48a6d3e8f9ebe3c3231c12cbe4b0c4ed4d24 (patch) | |
| tree | 89232d017899e647deb2a7ce58a45277c7c2998c | |
| parent | 3855ae1c486a2d1b65a96fac8d504ef7197e62cd (diff) | |
register_console: prevent adding the same console twice
This patch guards the console_drivers list to be corrupted. The
for_each_console() macro insist on a strictly forward list ended by NULL:
con0->next->con1->next->NULL
Without this patch it may happen easily to destroy this list for example by
adding 'earlyprintk' twice, especially on embedded devices where the early
console is often a single static instance. This will result in the following
list:
con0->next->con0
This in turn will result in an endless loop in console_unlock() later on by
printing the first __log_buf line endlessly.
Signed-off-by: Andreas Bießmann <andreas@biessmann.de>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/printk/printk.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 5b5a7080e2a..b4e8500afdb 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2226,6 +2226,13 @@ void register_console(struct console *newcon) struct console *bcon = NULL; struct console_cmdline *c; + if (console_drivers) + for_each_console(bcon) + if (WARN(bcon == newcon, + "console '%s%d' already registered\n", + bcon->name, bcon->index)) + return; + /* * before we register a new CON_BOOT console, make sure we don't * already have a valid console |