netdev - Re: 4.6.3, pppoe + shaper workload, skb_panic / skb_push / ppp_start

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: <e9486191e8af136c9ed4cc1cfc26ac9f@nuclearcat.com>
Date:	Tue, 12 Jul 2016 21:03:17 +0300
From:	nuclearcat@...learcat.com
To:	Cong Wang <xiyou.wangcong@...il.com>
Cc:	Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: 4.6.3, pppoe + shaper workload, skb_panic / skb_push /
 ppp_start_xmit

On 2016-07-12 20:31, Cong Wang wrote:
> On Mon, Jul 11, 2016 at 12:45 PM,  <nuclearcat@...learcat.com> wrote:
>> Hi
>> 
>> On latest kernel i noticed kernel panic happening 1-2 times per day. 
>> It is
>> also happening on older kernel (at least 4.5.3).
>> 
> ...
>>  [42916.426463] Call Trace:
>>  [42916.426658]  <IRQ>
>> 
>>  [42916.426719]  [<ffffffff81843786>] skb_push+0x36/0x37
>>  [42916.427111]  [<ffffffffa00e8ce5>] ppp_start_xmit+0x10f/0x150
>> [ppp_generic]
>>  [42916.427314]  [<ffffffff81853467>] dev_hard_start_xmit+0x25a/0x2d3
>>  [42916.427516]  [<ffffffff818530f2>] ?
>> validate_xmit_skb.isra.107.part.108+0x11d/0x238
>>  [42916.427858]  [<ffffffff8186dee3>] sch_direct_xmit+0x89/0x1b5
>>  [42916.428060]  [<ffffffff8186e142>] __qdisc_run+0x133/0x170
>>  [42916.428261]  [<ffffffff81850034>] net_tx_action+0xe3/0x148
>>  [42916.428462]  [<ffffffff810c401a>] __do_softirq+0xb9/0x1a9
>>  [42916.428663]  [<ffffffff810c4251>] irq_exit+0x37/0x7c
>>  [42916.428862]  [<ffffffff8102b8f7>] 
>> smp_apic_timer_interrupt+0x3d/0x48
>>  [42916.429063]  [<ffffffff818cb15c>] apic_timer_interrupt+0x7c/0x90
> 
> Interesting, we call a skb_cow_head() before skb_push() in 
> ppp_start_xmit(),
> I have no idea why this could happen.
> 
> Do you have any tc qdisc, filter or actions on this ppp device?
Yes, i have policing filters for incoming traffic (ingress), and also on 
egress htb + pfifo + filters.