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 <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: Kay Sievers <[email protected]> Cc: Ben Hutchings <[email protected]> Cc: [email protected] --- since v1: * use WARN() as Ben suggested * print 'already registered' instead of 'prevent registering' kernel/printk/printk.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 5b5a708..b4e8500 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 -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
