linux-kernel - Re: [PATCH -tip v6 06/22] [BUGFIX] x86: Prohibit probing on memcpy/memset

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Date:	Fri, 20 Dec 2013 11:37:49 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Jovi Zhangwei <jovi.zhangwei@...il.com>
Cc:	Ingo Molnar <mingo@...nel.org>, linux-arch@...r.kernel.org,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Sandeepa Prabhu <sandeepa.prabhu@...aro.org>, x86@...nel.org,
	lkml <linux-kernel@...r.kernel.org>,
	"Steven Rostedt (Red Hat)" <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...hat.com>, systemtap@...rceware.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH -tip v6 06/22] [BUGFIX] x86: Prohibit probing on memcpy/memset

Hi Jovi,

(2013/12/19 18:37), Jovi Zhangwei wrote:
> Hi Masami,
> 
> On Thu, Dec 19, 2013 at 5:04 PM, Masami Hiramatsu
> <masami.hiramatsu.pt@...achi.com> wrote:
>> memcpy/memset functions are fundamental functions and
>> those are involved in kprobe's exception handling.
>> Prohibit probing on them to avoid kernel crash.
>>
> Would you please let me know the LKML link of that bugfix, I cannot
> find it in my LKML fold.

Yeah, that was found in my testing environment.

> No objection on this patch. :) just want to know more, It seems there
> have no problem to probe memcpy in my box, maybe I didn't hit the
> crash code path.

Ah, I see. Originally the problem happened when I put a probe on
__memcpy. And it looks the instances of memcpy and __memcpy are
same on x86-64. Thus I decided to blacklist both. (memset/__memset too)
Have you ever tried to probe __memcpy on your box?

Thank you,

-- 
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com


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