netdev - Re: [RFC PATCH] bonding: use mutex lock in bond_get

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]

Date:   Sat, 16 Feb 2019 10:18:28 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>
Cc:     netdev <netdev@...r.kernel.org>,
        Willem de Bruijn <willemb@...gle.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jay Vosburgh <j.vosburgh@...il.com>,
        Veaceslav Falico <vfalico@...il.com>, weiyongjun1@...wei.com
Subject: Re: [RFC PATCH] bonding: use mutex lock in bond_get_stats()

On Fri, Feb 15, 2019 at 9:36 PM Kefeng Wang <wangkefeng.wang@...wei.com> wrote:
>
>
>
> On 2019/2/15 21:57, Eric Dumazet wrote:
> > On Fri, Feb 15, 2019 at 5:37 AM Kefeng Wang <wangkefeng.wang@...wei.com> wrote:
> >>
> >> With CONFIG_DEBUG_SPINLOCK=y, we find following stack,
> >>
> >>  BUG: spinlock wrong CPU on CPU#0, ip/16047
> >>   lock: 0xffff803f5febc998, .magic: dead4ead, .owner: ip/16047, .owner_cpu: 0
> >>  CPU: 1 PID: 16047 Comm: ip Kdump: loaded Tainted: G            E 4.19.12.aarch64 #1
> >>  Hardware name: Huawei TaiShan 2280 V2/BC82AMDA, BIOS TA BIOS TaiShan 2280 V2 - B900 01/29/2019
> >>  Call trace:
> >>   dump_backtrace+0x0/0x1c0
> >>   show_stack+0x24/0x30
> >>   dump_stack+0x90/0xbc
> >>   spin_dump+0x84/0xa8
> >>   do_raw_spin_unlock+0xf8/0x100
> >>   _raw_spin_unlock+0x20/0x30
> >>   bond_get_stats+0x110/0x140 [bonding]
> >>   rtnl_fill_stats+0x50/0x150
> >>   rtnl_fill_ifinfo+0x4d4/0xd18
> >>   rtnl_dump_ifinfo+0x200/0x3a8
> >>   netlink_dump+0x100/0x2b0
> >>   netlink_recvmsg+0x310/0x3e8
> >>   sock_recvmsg+0x58/0x68
> >>   ___sys_recvmsg+0xd0/0x278
> >>   __sys_recvmsg+0x74/0xd0
> >>   __arm64_sys_recvmsg+0x2c/0x38
> >>   el0_svc_common+0x7c/0x118
> >>   el0_svc_handler+0x30/0x40
> >>   el0_svc+0x8/0xc
> >>
> >> and then lead to softlockup issue, fix this by using mutex lock instead
> >> of spin lock.
> >>
> >> Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
> >> ---
> >>
> >> Not sure if this is right fix, please correct me if I'm wrong.
> >>
> >
> > Make sure to also try :
> >
> > cat /proc/net/dev
>
> Yes, no regression with this patch in our test or 'cat /proc/net/dev'
>

You really should have a warning showing up.

Make sure you have : DEBUG_ATOMIC_SLEEP=y  (I thought this was
automatically selected with LOCKDEP on, maybe not...)

Please take a look at net/core/net-procfs.c , functions
dev_seq_start(), dev_seq_printf_stats(), dev_seq_show()

We can not use a mutex in a section protected by rcu_read_lock()