linux-kernel - Re: call_rcu from trace

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <557FC822.2040405@bmw-carit.de>
Date:	Tue, 16 Jun 2015 08:54:26 +0200
From:	Daniel Wagner <daniel.wagner@...-carit.de>
To:	Alexei Starovoitov <ast@...mgrid.com>, <paulmck@...ux.vnet.ibm.com>
CC:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: call_rcu from trace_preempt

On 06/16/2015 08:46 AM, Alexei Starovoitov wrote:
> On 6/15/15 11:34 PM, Daniel Wagner wrote:
>> On 06/16/2015 08:25 AM, Alexei Starovoitov wrote:
>>> On 6/15/15 11:06 PM, Daniel Wagner wrote:
>>>>> with the above 'fix' the trace.patch is now passing.
>>>> It still crashes for me with the original test program
>>>>
>>>> [  145.908013]  [<ffffffff810d1da1>] ? __rcu_reclaim+0x101/0x3d0
>>>> [  145.908013]  [<ffffffff810d1ca0>] ? rcu_barrier_func+0x250/0x250
>>>> [  145.908013]  [<ffffffff810abc03>] ?
>>>> trace_hardirqs_on_caller+0xf3/0x240
>>>> [  145.908013]  [<ffffffff810d9afa>] rcu_do_batch+0x2ea/0x6b0
>>>
>>> yes. full bpf test still crashes.
>>> That's why I said trace.patch is passing ;)
>>> There is something else in there. One 'fix' at a time.
>>
>> Ah, sorry, I read it is working now :) Anyway, I'll keep looking
>> as well.
>>
>> Yesterday I wrote a small torture program for the map
>> implementation. Just to rule out memory corruption there.
>> Are you interested in it? If yes I could clean it a bit.
> 
> of course!
> We already have samples/bpf/test_maps.c that stresses map
> access from user space and lib/test_bpf.c that stress JIT
> and interpreter from the kernel.
> Looking at your test, I think it doesn't buy as much doing it
> from the kernel?

No, it doesn't really buy you anything compared to test_maps.c. I was
just ignored to the fact that test_maps.c exists. My goal was to reduce
the problem to a smallest unit and therefore tried to do it inside the
kernel without any additional layers.

> If so, I think would be great to add it to test_maps.c
> 
> Will read it more carefully tomorrow.

No need, test_maps.c is far better.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/