Message-ID: <CAK+SQuR+SutQ3fqsASVzPiSfCfyH5EtaJtn=ksvpg7TouVFDcQ@mail.gmail.com>
Date:   Sun, 20 Feb 2022 13:06:35 +0900
From:   Juhee Kang <claudiajkang@...il.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     patchwork-bot+netdevbpf@...nel.org, davem@...emloft.net,
        Jakub Kicinski <kuba@...nel.org>,
        Networking <netdev@...r.kernel.org>, ennoerlangen@...il.com,
        george.mccollister@...il.com, Vladimir Oltean <olteanv@...il.com>,
        marco.wenzel@...berle.de,
        syzbot+f0eb4f3876de066b128c@...kaller.appspotmail.com
Subject: Re: [PATCH net-next v3] net: hsr: fix suspicious RCU usage warning in hsr_node_get_first()

On Sun, Feb 20, 2022 at 11:55 AM Eric Dumazet <eric.dumazet@...il.com> wrote:
>
>
> On 2/19/22 08:50, patchwork-bot+netdevbpf@...nel.org wrote:
> > Hello:
> >
> > This patch was applied to netdev/net-next.git (master)
> > by David S. Miller <davem@...emloft.net>:
> >
> > On Sat, 19 Feb 2022 15:29:59 +0000 you wrote:
> >> When hsr_create_self_node() calls hsr_node_get_first(), the suspicious
> >> RCU usage warning is occurred. The reason why this warning is raised is
> >> the callers of hsr_node_get_first() use rcu_read_lock_bh() and
> >> other different synchronization mechanisms. Thus, this patch solved by
> >> replacing rcu_dereference() with rcu_dereference_bh_check().
> >>
> >> The kernel test robot reports:
> >>      [   50.083470][ T3596] =============================
> >>      [   50.088648][ T3596] WARNING: suspicious RCU usage
> >>      [   50.093785][ T3596] 5.17.0-rc3-next-20220208-syzkaller #0 Not tainted
> >>      [   50.100669][ T3596] -----------------------------
> >>      [   50.105513][ T3596] net/hsr/hsr_framereg.c:34 suspicious rcu_dereference_check() usage!
> >>      [   50.113799][ T3596]
> >>      [   50.113799][ T3596] other info that might help us debug this:
> >>      [   50.113799][ T3596]
> >>      [   50.124257][ T3596]
> >>      [   50.124257][ T3596] rcu_scheduler_active = 2, debug_locks = 1
> >>      [   50.132368][ T3596] 2 locks held by syz-executor.0/3596:
> >>      [   50.137863][ T3596]  #0: ffffffff8d3357e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x3be/0xb80
> >>      [   50.147470][ T3596]  #1: ffff88807ec9d5f0 (&hsr->list_lock){+...}-{2:2}, at: hsr_create_self_node+0x225/0x650
> >>      [   50.157623][ T3596]
> >>      [   50.157623][ T3596] stack backtrace:
> >>      [   50.163510][ T3596] CPU: 1 PID: 3596 Comm: syz-executor.0 Not tainted 5.17.0-rc3-next-20220208-syzkaller #0
> >>      [   50.173381][ T3596] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> >>      [   50.183623][ T3596] Call Trace:
> >>      [   50.186904][ T3596]  <TASK>
> >>      [   50.189844][ T3596]  dump_stack_lvl+0xcd/0x134
> >>      [   50.194640][ T3596]  hsr_node_get_first+0x9b/0xb0
> >>      [   50.199499][ T3596]  hsr_create_self_node+0x22d/0x650
> >>      [   50.204688][ T3596]  hsr_dev_finalize+0x2c1/0x7d0
> >>      [   50.209669][ T3596]  hsr_newlink+0x315/0x730
> >>      [   50.214113][ T3596]  ? hsr_dellink+0x130/0x130
> >>      [   50.218789][ T3596]  ? rtnl_create_link+0x7e8/0xc00
> >>      [   50.223803][ T3596]  ? hsr_dellink+0x130/0x130
> >>      [   50.228397][ T3596]  __rtnl_newlink+0x107c/0x1760
> >>      [   50.233249][ T3596]  ? rtnl_setlink+0x3c0/0x3c0
> >>      [   50.238043][ T3596]  ? is_bpf_text_address+0x77/0x170
> >>      [   50.243362][ T3596]  ? lock_downgrade+0x6e0/0x6e0
> >>      [   50.248219][ T3596]  ? unwind_next_frame+0xee1/0x1ce0
> >>      [   50.253605][ T3596]  ? entry_SYSCALL_64_after_hwframe+0x44/0xae
> >>      [   50.259669][ T3596]  ? __sanitizer_cov_trace_cmp4+0x1c/0x70
> >>      [   50.265423][ T3596]  ? is_bpf_text_address+0x99/0x170
> >>      [   50.270819][ T3596]  ? kernel_text_address+0x39/0x80
> >>      [   50.275950][ T3596]  ? __kernel_text_address+0x9/0x30
> >>      [   50.281336][ T3596]  ? unwind_get_return_address+0x51/0x90
> >>      [   50.286975][ T3596]  ? create_prof_cpu_mask+0x20/0x20
> >>      [   50.292178][ T3596]  ? arch_stack_walk+0x93/0xe0
> >>      [   50.297172][ T3596]  ? kmem_cache_alloc_trace+0x42/0x2c0
> >>      [   50.302637][ T3596]  ? rcu_read_lock_sched_held+0x3a/0x70
> >>      [   50.308194][ T3596]  rtnl_newlink+0x64/0xa0
> >>      [   50.312524][ T3596]  ? __rtnl_newlink+0x1760/0x1760
> >>      [   50.317545][ T3596]  rtnetlink_rcv_msg+0x413/0xb80
> >>      [   50.322631][ T3596]  ? rtnl_newlink+0xa0/0xa0
> >>      [   50.327159][ T3596]  netlink_rcv_skb+0x153/0x420
> >>      [   50.331931][ T3596]  ? rtnl_newlink+0xa0/0xa0
> >>      [   50.336436][ T3596]  ? netlink_ack+0xa80/0xa80
> >>      [   50.341095][ T3596]  ? netlink_deliver_tap+0x1a2/0xc40
> >>      [   50.346532][ T3596]  ? netlink_deliver_tap+0x1b1/0xc40
> >>      [   50.351839][ T3596]  netlink_unicast+0x539/0x7e0
> >>      [   50.356633][ T3596]  ? netlink_attachskb+0x880/0x880
> >>      [   50.361750][ T3596]  ? __sanitizer_cov_trace_const_cmp8+0x1d/0x70
> >>      [   50.368003][ T3596]  ? __sanitizer_cov_trace_const_cmp8+0x1d/0x70
> >>      [   50.374707][ T3596]  ? __phys_addr_symbol+0x2c/0x70
> >>      [   50.379753][ T3596]  ? __sanitizer_cov_trace_cmp8+0x1d/0x70
> >>      [   50.385568][ T3596]  ? __check_object_size+0x16c/0x4f0
> >>      [   50.390859][ T3596]  netlink_sendmsg+0x904/0xe00
> >>      [   50.395715][ T3596]  ? netlink_unicast+0x7e0/0x7e0
> >>      [   50.400722][ T3596]  ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70
> >>      [   50.407003][ T3596]  ? netlink_unicast+0x7e0/0x7e0
> >>      [   50.412119][ T3596]  sock_sendmsg+0xcf/0x120
> >>      [   50.416548][ T3596]  __sys_sendto+0x21c/0x320
> >>      [   50.421052][ T3596]  ? __ia32_sys_getpeername+0xb0/0xb0
> >>      [   50.426427][ T3596]  ? lockdep_hardirqs_on_prepare+0x400/0x400
> >>      [   50.432721][ T3596]  ? __context_tracking_exit+0xb8/0xe0
> >>      [   50.438188][ T3596]  ? lock_downgrade+0x6e0/0x6e0
> >>      [   50.443041][ T3596]  ? lock_downgrade+0x6e0/0x6e0
> >>      [   50.447902][ T3596]  __x64_sys_sendto+0xdd/0x1b0
> >>      [   50.452759][ T3596]  ? lockdep_hardirqs_on+0x79/0x100
> >>      [   50.457964][ T3596]  ? syscall_enter_from_user_mode+0x21/0x70
> >>      [   50.464150][ T3596]  do_syscall_64+0x35/0xb0
> >>      [   50.468565][ T3596]  entry_SYSCALL_64_after_hwframe+0x44/0xae
> >>      [   50.474452][ T3596] RIP: 0033:0x7f3148504e1c
> >>      [   50.479052][ T3596] Code: fa fa ff ff 44 8b 4c 24 2c 4c 8b 44 24 20 89 c5 44 8b 54 24 28 48 8b 54 24 18 b8 2c 00 00 00 48 8b 74 24 10 8b 7c 24 08 0f 05 <48> 3d 00 f0 ff ff 77 34 89 ef 48 89 44 24 08 e8 20 fb ff ff 48 8b
> >>      [   50.498926][ T3596] RSP: 002b:00007ffeab5f2ab0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
> >>      [   50.507342][ T3596] RAX: ffffffffffffffda RBX: 00007f314959d320 RCX: 00007f3148504e1c
> >>      [   50.515393][ T3596] RDX: 0000000000000048 RSI: 00007f314959d370 RDI: 0000000000000003
> >>      [   50.523444][ T3596] RBP: 0000000000000000 R08: 00007ffeab5f2b04 R09: 000000000000000c
> >>      [   50.531492][ T3596] R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
> >>      [   50.539455][ T3596] R13: 00007f314959d370 R14: 0000000000000003 R15: 0000000000000000
> >>
> >> [...]
> > Here is the summary with links:
> >    - [net-next,v3] net: hsr: fix suspicious RCU usage warning in hsr_node_get_first()
> >      https://git.kernel.org/netdev/net-next/c/e7f27420681f
> >
> > You are awesome, thank you!
>
>
> This patch broke the build, please revert or fix.
>
>
> ERROR: modpost: "lockdep_is_held" [net/hsr/hsr.ko] undefined!
>
>
>
>

Hi Eric,
Thank you.

I will send a new patch after some tests.

Thank you so much.
-- 

Best regards,
Juhee Kang

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