Subject: possible deadlock in rtnl_lock (4)

From: syzbot <[email-masked]>
Date: Wed, 07 Feb 2018 14:58:01 -0800

Hello,

syzbot hit the following crash on upstream commit
a2e5790d841658485d642196dbb0927303d6c22f (Wed Feb 7 06:15:42 2018 +0000)
Merge branch 'akpm' (patches from Andrew)

So far this crash happened 632 times on  
https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master.
C reproducer is attached.
syzkaller reproducer is attached.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.

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Reported-by: [email-masked]
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======================================================
WARNING: possible circular locking dependency detected
4.15.0+ #301 Not tainted
------------------------------------------------------
syzkaller233489/4179 is trying to acquire lock:
  (rtnl_mutex){+.+.}, at: [<0000000048e996fd>] rtnl_lock+0x17/0x20  
net/core/rtnetlink.c:74

but task is already holding lock:
  (&xt[i].mutex){+.+.}, at: [<00000000328553a2>]  
xt_find_table_lock+0x3e/0x3e0 net/netfilter/x_tables.c:1041

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (&xt[i].mutex){+.+.}:
        __mutex_lock_common kernel/locking/mutex.c:756 [inline]
        __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
        mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
        xt_find_table_lock+0x3e/0x3e0 net/netfilter/x_tables.c:1041
        xt_request_find_table_lock+0x28/0xc0 net/netfilter/x_tables.c:1088
        get_info+0x154/0x690 net/ipv6/netfilter/ip6_tables.c:989
        do_ipt_get_ctl+0x159/0xac0 net/ipv4/netfilter/ip_tables.c:1699
        nf_sockopt net/netfilter/nf_sockopt.c:104 [inline]
        nf_getsockopt+0x6a/0xc0 net/netfilter/nf_sockopt.c:122
        ip_getsockopt+0x15c/0x220 net/ipv4/ip_sockglue.c:1571
        tcp_getsockopt+0x82/0xd0 net/ipv4/tcp.c:3359
        sock_common_getsockopt+0x95/0xd0 net/core/sock.c:2934
        SYSC_getsockopt net/socket.c:1880 [inline]
        SyS_getsockopt+0x178/0x340 net/socket.c:1862
        do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287
        entry_SYSCALL_64_after_hwframe+0x26/0x9b

-> #1 (sk_lock-AF_INET){+.+.}:
        lock_sock_nested+0xc2/0x110 net/core/sock.c:2777
        lock_sock include/net/sock.h:1463 [inline]
        do_ip_setsockopt.isra.12+0x1d9/0x3210 net/ipv4/ip_sockglue.c:646
        ip_setsockopt+0x3a/0xa0 net/ipv4/ip_sockglue.c:1252
        udp_setsockopt+0x45/0x80 net/ipv4/udp.c:2401
        sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2975
        SYSC_setsockopt net/socket.c:1849 [inline]
        SyS_setsockopt+0x189/0x360 net/socket.c:1828
        do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287
        entry_SYSCALL_64_after_hwframe+0x26/0x9b

-> #0 (rtnl_mutex){+.+.}:
        lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
        __mutex_lock_common kernel/locking/mutex.c:756 [inline]
        __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
        mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
        rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74
        unregister_netdevice_notifier+0x91/0x4e0 net/core/dev.c:1673
        clusterip_config_entry_put net/ipv4/netfilter/ipt_CLUSTERIP.c:114  
[inline]
        clusterip_tg_destroy+0x389/0x6e0  
net/ipv4/netfilter/ipt_CLUSTERIP.c:518
        cleanup_entry+0x218/0x350 net/ipv4/netfilter/ip_tables.c:654
        __do_replace+0x79d/0xa50 net/ipv4/netfilter/ip_tables.c:1089
        do_replace net/ipv4/netfilter/ip_tables.c:1145 [inline]
        do_ipt_set_ctl+0x40f/0x5f0 net/ipv4/netfilter/ip_tables.c:1675
        nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
        nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:115
        ip_setsockopt+0x97/0xa0 net/ipv4/ip_sockglue.c:1259
        tcp_setsockopt+0x82/0xd0 net/ipv4/tcp.c:2905
        sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2975
        SYSC_setsockopt net/socket.c:1849 [inline]
        SyS_setsockopt+0x189/0x360 net/socket.c:1828
        do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287
        entry_SYSCALL_64_after_hwframe+0x26/0x9b

other info that might help us debug this:

Chain exists of:
   rtnl_mutex --> sk_lock-AF_INET --> &xt[i].mutex

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&xt[i].mutex);
                                lock(sk_lock-AF_INET);
                                lock(&xt[i].mutex);
   lock(rtnl_mutex);

  *** DEADLOCK ***

1 lock held by syzkaller233489/4179:
  #0:  (&xt[i].mutex){+.+.}, at: [<00000000328553a2>]  
xt_find_table_lock+0x3e/0x3e0 net/netfilter/x_tables.c:1041

stack backtrace:
CPU: 1 PID: 4179 Comm: syzkaller233489 Not tainted 4.15.0+ #301
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x194/0x257 lib/dump_stack.c:53
  print_circular_bug.isra.38+0x2cd/0x2dc kernel/locking/lockdep.c:1223
  check_prev_add kernel/locking/lockdep.c:1863 [inline]
  check_prevs_add kernel/locking/lockdep.c:1976 [inline]
  validate_chain kernel/locking/lockdep.c:2417 [inline]
  __lock_acquire+0x30a8/0x3e00 kernel/locking/lockdep.c:3431
  lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
  __mutex_lock_common kernel/locking/mutex.c:756 [inline]
  __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
  rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74
  unregister_netdevice_notifier+0x91/0x4e0 net/core/dev.c:1673
  clusterip_config_entry_put net/ipv4/netfilter/ipt_CLUSTERIP.c:114 [inline]
  clusterip_tg_destroy+0x389/0x6e0 net/ipv4/netfilter/ipt_CLUSTERIP.c:518
  cleanup_entry+0x218/0x350 net/ipv4/netfilter/ip_tables.c:654
  __do_replace+0x79d/0xa50 net/ipv4/netfilter/ip_tables.c:1089
  do_replace net/ipv4/netfilter/ip_tables.c:1145 [inline]
  do_ipt_set_ctl+0x40f/0x5f0 net/ipv4/netfilter/ip_tables.c:1675
  nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
  nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:115
  ip_setsockopt+0x97/0xa0 net/ipv4/ip_sockglue.c:1259
  tcp_setsockopt+0x82/0xd0 net/ipv4/tcp.c:2905
  sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2975
  SYSC_setsockopt net/socket.c:1849 [inline]
  SyS_setsockopt+0x189/0x360 net/socket.c:1828
  do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x26/0x9b
RIP: 0033:0x44428a
RSP: 002b:00007fff903974a8 EFLAGS: 00000206 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000006cc100 RCX: 000000000044428a
RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00000000006cc100 R08: 00000000000002d8 R09: 0000000000cbe880
R10: 00000000006cc528 R11: 0000000000000206 R12: 0000000000000003
R13: 00000000006cf0a8 R14: 00000000006cf050 R15: 00000000004a322e

---
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