* Re: [PATCH v2] register_console: prevent adding the same console twice
[not found] <1364201964-2990-1-git-send-email-andreas@biessmann.de>
@ 2013-05-07 7:18 ` Andreas Bießmann
2013-08-02 10:23 ` [RESEND][PATCH " Andreas Bießmann
1 sibling, 0 replies; 3+ messages in thread
From: Andreas Bießmann @ 2013-05-07 7:18 UTC (permalink / raw)
To: Andreas Bießmann
Cc: linux-kernel, Greg Kroah-Hartman, Kay Sievers, Ben Hutchings,
stable
ping?
Am 2013-03-25 09:59, schrieb Andreas Bießmann:
> 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Kay Sievers <kay@vrfy.org>
> Cc: Ben Hutchings <ben@decadent.org.uk>
> Cc: stable@kernel.org
> ---
> since v1:
> * use WARN() as Ben suggested
> * print 'already registered' instead of 'prevent registering'
>
> kernel/printk.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/kernel/printk.c b/kernel/printk.c
> index abbdd9e..180ee25 100644
> --- a/kernel/printk.c
> +++ b/kernel/printk.c
> @@ -2214,6 +2214,13 @@ void register_console(struct console *newcon)
> unsigned long flags;
> struct console *bcon = NULL;
>
> + 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
^ permalink raw reply [flat|nested] 3+ messages in thread* [RESEND][PATCH v2] register_console: prevent adding the same console twice
[not found] <1364201964-2990-1-git-send-email-andreas@biessmann.de>
2013-05-07 7:18 ` [PATCH v2] register_console: prevent adding the same console twice Andreas Bießmann
@ 2013-08-02 10:23 ` Andreas Bießmann
2013-08-02 10:37 ` Greg Kroah-Hartman
1 sibling, 1 reply; 3+ messages in thread
From: Andreas Bießmann @ 2013-08-02 10:23 UTC (permalink / raw)
To: linux-kernel
Cc: Andreas Bießmann, Greg Kroah-Hartman, Kay Sievers,
Ben Hutchings, stable
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org
---
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
^ permalink raw reply related [flat|nested] 3+ messages in thread