Date:	Thu, 21 Nov 2013 01:34:10 +0800
From:	Peng Tao <bergwolf@...il.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Amir Shehata <amir.shehata@...el.com>,
	Andreas Dilger <andreas.dilger@...el.com>
Subject: Re: [PATCH 4/9] staging/lustre/lnet: Fix assert on empty group in
 selftest module

On 11/21/2013 12:27 AM, Greg Kroah-Hartman wrote:
> On Wed, Nov 20, 2013 at 05:26:57PM +0800, Peng Tao wrote:
>> On Wed, Nov 20, 2013 at 2:37 AM, Greg Kroah-Hartman
>> <gregkh@...uxfoundation.org> wrote:
>>> On Tue, Nov 19, 2013 at 09:23:43PM +0800, Peng Tao wrote:
>>>> From: Amir Shehata <amir.shehata@...el.com>
>>>>
>>>> The core of the issue is that the selftest module doesn't sanitize its
>>>> own API, but it depends on lst utility to do such checks.  As a result
>>>> this issue manifests itself in this particular LU through an assert
>>>> on an empty group.  If the NID is misspelled then an empty group is
>>>> added.  An error output is provided, but if that's never checked in a
>>>> batch script, as is the case with this issue, then the script will try
>>>> to add an empty group to a test to run in a batch, and that will cause
>>>> an assert
>>>>
>>>> The fix is two fold.  Ensure that lst utility checks that a group is
>>>> added with at least one node.  If not the group is subsequently
>>>> deleted.  And the add_test command would fail, since the group no
>>>> longer exists.
>>>>
>>>> The second fix is to ensure that the kernel module itself sanitizes
>>>> its own API in this particular case, so that if a different utility is
>>>> used other than lst to communicate with the selftest kernel module
>>>> then this error would be caught.  This fix looks up the batch and the
>>>> groups, src and dst, in the ioctl handle and sanitizes that input at
>>>> this point.  If the group looked up either doesn't exist or doesn't
>>>> have at least one ACTIVE node, then the command fails.
>>>>
>>>> NOTE:there are many other cases in the code where the selftest kernel
>>>> module doesn't check for sanity of the input, but depends totally on
>>>> the lst module to do such checks.  Particularly around length of
>>>> strings passed in.  Thus it is possible to crash the selftest module
>>>> if someone tries to create another userspace app to communicate with
>>>> the selftest kernel module without ensuring sanity of the params sent
>>>> to the kernel module.  In effect, it's always assumed that lst is the
>>>> front end for selftest and no other front end is to be used.
>>> This patch adds build warnings to the kernel build process, so I can't
>>> apply it, sorry.  Please fix that up before sending it again.
>>>
>> Hi Greg,
>>
>> Can you please be explicit about what build warning you saw?
> I don't remember what it was at the moment, sorry.
>
>> I tried to reproduce it with gcc version 4.1.2 and 4.6.3 on my
>> machine, but didn't see any build warnings with this patch applied.
> I have 4.7.3 here, and x86-64.  Try that and see what happens.
>
Could you please share you .config? I just tried gcc 4.7.3 on x86_64 but 
still no luck. Guess it might have something to do with certain Kconfig 
combinations.

[X61@...ux-lustre]$gcc --version
gcc (Ubuntu/Linaro 4.7.3-1ubuntu1) 4.7.3
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[X61@...ux-lustre]$uname -a
Linux X61 3.11.0 #1 SMP Wed Sep 4 23:16:15 CST 2013 x86_64 x86_64 x86_64 
GNU/Linux

Thanks,
Tao
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