linux-kernel - Re: net/ipv4: deadlock in ip_ra

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Date:   Fri, 3 Mar 2017 19:43:52 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     David Miller <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        James Morris <jmorris@...ei.org>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Patrick McHardy <kaber@...sh.net>,
        Eric Dumazet <edumazet@...gle.com>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: net/ipv4: deadlock in ip_ra_control

On Thu, Mar 2, 2017 at 10:40 AM, Dmitry Vyukov <dvyukov@...gle.com> wrote:
> On Wed, Mar 1, 2017 at 6:18 PM, Cong Wang <xiyou.wangcong@...il.com> wrote:
>> On Wed, Mar 1, 2017 at 2:44 AM, Dmitry Vyukov <dvyukov@...gle.com> wrote:
>>> Hello,
>>>
>>> I've got the following deadlock report while running syzkaller fuzzer
>>> on linux-next/51788aebe7cae79cb334ad50641347465fc188fd:
>>>
>>> ======================================================
>>> [ INFO: possible circular locking dependency detected ]
>>> 4.10.0-next-20170301+ #1 Not tainted
>>> -------------------------------------------------------
>>> syz-executor1/3394 is trying to acquire lock:
>>>  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff838864cc>] lock_sock
>>> include/net/sock.h:1460 [inline]
>>>  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff838864cc>]
>>> do_ip_setsockopt.isra.12+0x21c/0x3540 net/ipv4/ip_sockglue.c:652
>>>
>>> but task is already holding lock:
>>>  (rtnl_mutex){+.+.+.}, at: [<ffffffff836fbd97>] rtnl_lock+0x17/0x20
>>> net/core/rtnetlink.c:70
>>>
>>> which lock already depends on the new lock.
>>>
>>>
>>> the existing dependency chain (in reverse order) is:
>>>
>>> -> #1 (rtnl_mutex){+.+.+.}:
>>>        validate_chain kernel/locking/lockdep.c:2265 [inline]
>>>        __lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3338
>>>        lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3753
>>>        __mutex_lock_common kernel/locking/mutex.c:754 [inline]
>>>        __mutex_lock+0x172/0x1730 kernel/locking/mutex.c:891
>>>        mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:906
>>>        rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
>>>        mrtsock_destruct+0x86/0x2c0 net/ipv4/ipmr.c:1281
>>>        ip_ra_control+0x459/0x600 net/ipv4/ip_sockglue.c:372
>>>        do_ip_setsockopt.isra.12+0x1064/0x3540 net/ipv4/ip_sockglue.c:1161
>>>        ip_setsockopt+0x3a/0xb0 net/ipv4/ip_sockglue.c:1264
>>>        raw_setsockopt+0xb7/0xd0 net/ipv4/raw.c:839
>>>        sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2725
>>>        SYSC_setsockopt net/socket.c:1786 [inline]
>>>        SyS_setsockopt+0x25c/0x390 net/socket.c:1765
>>>        entry_SYSCALL_64_fastpath+0x1f/0xc2
>>>
>>> -> #0 (sk_lock-AF_INET){+.+.+.}:
>>>        check_prev_add kernel/locking/lockdep.c:1828 [inline]
>>>        check_prevs_add+0xa8f/0x19f0 kernel/locking/lockdep.c:1938
>>>        validate_chain kernel/locking/lockdep.c:2265 [inline]
>>>        __lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3338
>>>        lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3753
>>>        lock_sock_nested+0xcb/0x120 net/core/sock.c:2530
>>>        lock_sock include/net/sock.h:1460 [inline]
>>>        do_ip_setsockopt.isra.12+0x21c/0x3540 net/ipv4/ip_sockglue.c:652
>>>        ip_setsockopt+0x3a/0xb0 net/ipv4/ip_sockglue.c:1264
>>>        tcp_setsockopt+0x82/0xd0 net/ipv4/tcp.c:2721
>>>        sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2725
>>>        SYSC_setsockopt net/socket.c:1786 [inline]
>>>        SyS_setsockopt+0x25c/0x390 net/socket.c:1765
>>>        entry_SYSCALL_64_fastpath+0x1f/0xc2
>>>
>>
>> Please try the attached patch (compile only).
>
>
> Pushed the patch to the bots.
> Thanks


This patch triggers:

[   57.748990] RTNL: assertion failed at net/ipv4/ipmr.c (1236)
[   57.749022] CPU: 1 PID: 5301 Comm: syz-executor2 Not tainted 4.10.0+ #15
[   57.749026] Hardware name: Google Google Compute Engine/Google
Compute Engine, BIOS Google 01/01/2011
[   57.749028] Call Trace:
[   57.749042]  dump_stack+0x2ee/0x3ef
[   57.749219]  mrtsock_destruct+0x27e/0x2f0
[   57.749241]  ip_ra_control+0x459/0x600
[   57.749287]  raw_close+0x19/0x30
[   57.749295]  inet_release+0xed/0x1c0
[   57.749303]  sock_release+0x8d/0x1e0
[   57.749316]  sock_close+0x16/0x20
[   57.749323]  __fput+0x332/0x7f0
[   57.749340]  ____fput+0x15/0x20
[   57.749347]  task_work_run+0x18a/0x260
[   57.749372]  do_exit+0x18ef/0x28b0
[   57.749641]  do_group_exit+0x149/0x420
[   57.749656]  get_signal+0x7e0/0x1820
[   57.749697]  do_signal+0xd2/0x2190
[   57.749746]  exit_to_usermode_loop+0x200/0x2a0
[   57.749758]  syscall_return_slowpath+0x4d3/0x570
[   57.749835]  entry_SYSCALL_64_fastpath+0xc0/0xc2
[   57.749840] RIP: 0033:0x44fb79
[   57.749843] RSP: 002b:00007fbba84d9cf8 EFLAGS: 00000246 ORIG_RAX:
00000000000000ca
[   57.749850] RAX: fffffffffffffe00 RBX: 0000000000708218 RCX: 000000000044fb79
[   57.749854] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000708218
[   57.749857] RBP: 00000000007081f8 R08: 0000000000000000 R09: 0000000000000000
[   57.749860] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[   57.749864] R13: 0000000000a5fc57 R14: 00007fbba84da9c0 R15: 000000000000000c
[   57.749964]
[   57.749966] ===============================
[   57.749967] [ INFO: suspicious RCU usage. ]
[   57.749971] 4.10.0+ #15 Not tainted
[   57.749972] -------------------------------
[   57.749975] net/ipv4/ipmr.c:1238 suspicious
rcu_dereference_protected() usage!
[   57.749977]
[   57.749977] other info that might help us debug this:
[   57.749977]
[   57.749980]
[   57.749980] rcu_scheduler_active = 2, debug_locks = 0
[   57.749982] no locks held by syz-executor2/5301.
[   57.749984]
[   57.749984] stack backtrace:
[   57.749989] CPU: 1 PID: 5301 Comm: syz-executor2 Not tainted 4.10.0+ #15
[   57.749993] Hardware name: Google Google Compute Engine/Google
Compute Engine, BIOS Google 01/01/2011
[   57.749995] Call Trace:
[   57.750001]  dump_stack+0x2ee/0x3ef
[   57.750117]  lockdep_rcu_suspicious+0x139/0x180
[   57.750122]  mrtsock_destruct+0x167/0x2f0
[   57.750144]  ip_ra_control+0x459/0x600
[   57.750182]  raw_close+0x19/0x30
[   57.750188]  inet_release+0xed/0x1c0
[   57.750194]  sock_release+0x8d/0x1e0
[   57.750208]  sock_close+0x16/0x20
[   57.750213]  __fput+0x332/0x7f0
[   57.750228]  ____fput+0x15/0x20
[   57.750233]  task_work_run+0x18a/0x260
[   57.750256]  do_exit+0x18ef/0x28b0
[   57.750499]  do_group_exit+0x149/0x420
[   57.750515]  get_signal+0x7e0/0x1820
[   57.750556]  do_signal+0xd2/0x2190
[   57.750604]  exit_to_usermode_loop+0x200/0x2a0
[   57.750616]  syscall_return_slowpath+0x4d3/0x570
[   57.750693]  entry_SYSCALL_64_fastpath+0xc0/0xc2
[   57.750698] RIP: 0033:0x44fb79
[   57.750701] RSP: 002b:00007fbba84d9cf8 EFLAGS: 00000246 ORIG_RAX:
00000000000000ca
[   57.750708] RAX: fffffffffffffe00 RBX: 0000000000708218 RCX: 000000000044fb79
[   57.750712] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000708218
[   57.750716] RBP: 00000000007081f8 R08: 0000000000000000 R09: 0000000000000000
[   57.750720] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[   57.750724] R13: 0000000000a5fc57 R14: 00007fbba84da9c0 R15: 000000000000000c