linux-kernel - Re: [PATCH] printk: fix possible reuse of va

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Date:   Thu, 17 May 2018 13:57:52 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc:     sergey.senozhatsky.work@...il.com, dvyukov@...gle.com,
        sergey.senozhatsky@...il.com, syzkaller@...glegroups.com,
        rostedt@...dmis.org, fengguang.wu@...el.com,
        linux-kernel@...r.kernel.org, peterz@...radead.org
Subject: Re: [PATCH] printk: fix possible reuse of va_list variable

On Fri 2018-05-11 20:02:31, Tetsuo Handa wrote:
> >From 766cf72b5fdc00d1cf5a8ca2c6b23ebb75e2b4d4 Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> Date: Fri, 11 May 2018 19:54:19 +0900
> Subject: [PATCH] printk: fix possible reuse of va_list variable
> 
> I noticed that there is a possibility that printk_safe_log_store() causes
> kernel oops because "args" parameter is passed to vsnprintf() again when
> atomic_cmpxchg() detected that we raced. Fix this by using va_copy().

Great catch!

Reviewed-by: Petr Mladek <pmladek@...e.com>

I have tagged it for stable and pushed into printk.git,
branch for-4.18, see
https://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk.git/commit/?h=for-4.18&id=988a35f8da1dec5a8cd2788054d1e717be61bf25

Best Regards,
Petr