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: <20140306.131310.1830419590852091525.davem@davemloft.net>
Date:	Thu, 06 Mar 2014 13:13:10 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	sergey.senozhatsky@...il.com
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: use raw_cpu ops in snmp stats bh

From: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Date: Thu,  6 Mar 2014 15:55:36 +0300

> Commit a25982c15ae52 ("percpu: add preemption checks to __this_cpu
> ops") added preemption checks to __this_cpu ops, which are used in
> SNMP_INC_STATS_BH() and SNMP_ADD_STATS_BH(), resulting in following
> warnings:
> 
> BUG: using __this_cpu_add() in preemptible [00000000] code: ssh/4661
> caller is __this_cpu_preempt_check+0x2b/0x2d
> CPU: 3 PID: 4661 Comm: ssh Not tainted 3.14.0-rc5-next-20140306-dbg-dirty #162
> Hardware name: Acer             Aspire 5741G    /Aspire 5741G    , BIOS V1.20 02/08/2011
>  0000000000000000 ffff880094939be0 ffffffff813b8305 0000000000000003
>  ffff880094939c00 ffffffff8121221f ffff88015130a8c0 0000000000000000
>  ffff880094939c38 ffffffff8121226b 635f736968745f5f 29286464615f7570
> Call Trace:
>  [<ffffffff813b8305>] dump_stack+0x4e/0x7a
>  [<ffffffff8121221f>] check_preemption_disabled+0xce/0xdd
>  [<ffffffff8121226b>] __this_cpu_preempt_check+0x2b/0x2d
>  [<ffffffff81370b5a>] ? tcp_rearm_rto+0x9f/0xa1
>  [<ffffffff81373456>] tcp_event_new_data_sent+0x6d/0x91
>  [<ffffffff81374dc6>] tcp_write_xmit+0x3f1/0x935
>  [<ffffffff813754e4>] __tcp_push_pending_frames+0x28/0x82
>  [<ffffffff81368109>] tcp_push+0xcc/0x102
>  [<ffffffff8136a0c1>] tcp_sendmsg+0x8c5/0xb7a
>  [<ffffffff81207d59>] ? string.isra.6+0x3b/0x9f
>  [<ffffffff8138a10a>] inet_sendmsg+0x75/0xa0
>  [<ffffffff81320fb6>] sock_aio_write+0xe7/0xfe
>  [<ffffffff81207d59>] ? string.isra.6+0x3b/0x9f
>  [<ffffffff810e08ab>] do_sync_write+0x54/0x73
>  [<ffffffff810e0df7>] vfs_write+0xc6/0x17c
>  [<ffffffff810e1603>] SyS_write+0x44/0x78
>  [<ffffffff813be0a1>] tracesys+0xd4/0xd9
> 
> use raw_cpu_inc() and raw_cpu_add() instead of __this_cpu_inc()
> and __this_cpu_add().
> 
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>

This is a bug in the TCP code, if this code path can happen outside of
software interrupts or BH protected sections, which it can as seen in
this trace, it must use the non-_BH-postfixed versions of the SNMP
counter bumps.
--
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/

Powered by blists - more mailing lists