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From: Satoru Takeuchi <satoru.takeuchi@gmail.com>
To: Alexandre SIMON <Alexandre.Simon@univ-lorraine.fr>
Cc: Satoru Takeuchi <satoru.takeuchi@gmail.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [ 1/1] printk: fix buffer overflow when calling log_prefix function from call_console_drivers
Date: Thu, 21 Feb 2013 00:56:08 +0900	[thread overview]
Message-ID: <871ucbgesn.wl%satoru.takeuchi@gmail.com> (raw)
In-Reply-To: <5124D2ED.1090703@univ-lorraine.fr>

At Wed, 20 Feb 2013 14:43:09 +0100,
Alexandre SIMON wrote:
> 
> [Satoru Takeuchi] wrote the following on [20/02/2013 14:02]:
> [...]
> > 
> > I reviewed this patch and it seems to be good for me. Since I'm not good at
> > printk code, I want to confirm whether what I think is correct or not.
> > Is the following my understanding correct?
> 
>   No problem, it's nice to talk about this patch !
...
> > In this case, only LOG_BUF(cur_index) is safe to access and
> > 
> >  - "LOG_BUF(cur_index) + 1" as p[1],
> >  - "LOG_BUF(cur_index) + 2" as p[2], and
> >  - "LOG_BUF(cur_index) + 1 or more" as simple_strtoul(&p[1], &endp, 10)
> > 
> > in log_prefix() are not to do so. Hence touching them would cause the system hang as you
> > said as follows.
> 
>   Yes, your analyze is totally right. Your figure is clear and shows exactly when the problem occurs in the "borderline case".
>   The initial code does not check that the "cur_index" can be at the end of "log_buf" whereas "log_prefix" function may access to one, two or more indexes after.

Alex, thank you for quick response and the detailed explanation.
Greg, then I can say this patch looks correct and 3.0.66-rc1 version is too.

Thanks,
Satoru

  reply	other threads:[~2013-02-20 15:56 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-18 18:24 [ 0/1] 3.4.33-stable review Greg Kroah-Hartman
2013-02-18 18:24 ` [ 1/1] printk: fix buffer overflow when calling log_prefix function from call_console_drivers Greg Kroah-Hartman
2013-02-20 13:02   ` Satoru Takeuchi
2013-02-20 13:43     ` Alexandre SIMON
2013-02-20 15:56       ` Satoru Takeuchi [this message]
2013-02-19  2:50 ` [ 0/1] 3.4.33-stable review Shuah Khan
2013-02-20  2:51   ` Greg Kroah-Hartman
2013-02-20  3:31     ` Shuah Khan
2013-02-20 13:09       ` Satoru Takeuchi
2013-02-18 18:25 [ 0/1] 3.0.66-stable review Greg Kroah-Hartman
2013-02-18 18:25 ` [ 1/1] printk: fix buffer overflow when calling log_prefix function from call_console_drivers Greg Kroah-Hartman

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