syzbot

======================================================
WARNING: possible circular locking dependency detected
4.15.0+ #300 Not tainted
------------------------------------------------------
syzkaller428858/4154 is trying to acquire lock:
 (rtnl_mutex){+.+.}, at: [<00000000da6f19c2>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74

but task is already holding lock:
 (&xt[i].mutex){+.+.}, at: [<0000000097c1c439>] 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_ip6t_get_ctl+0x159/0xaf0 net/ipv6/netfilter/ip6_tables.c:1710
       nf_sockopt net/netfilter/nf_sockopt.c:104 [inline]
       nf_getsockopt+0x6a/0xc0 net/netfilter/nf_sockopt.c:122
       ipv6_getsockopt+0x1df/0x2e0 net/ipv6/ipv6_sockglue.c:1371
       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_INET6){+.+.}:
       lock_sock_nested+0xc2/0x110 net/core/sock.c:2777
       lock_sock include/net/sock.h:1463 [inline]
       do_ipv6_setsockopt.isra.8+0x3c5/0x39d0 net/ipv6/ipv6_sockglue.c:167
       ipv6_setsockopt+0xd7/0x130 net/ipv6/ipv6_sockglue.c:922
       dccp_setsockopt+0x85/0xd0 net/dccp/proto.c:576
       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_INET6 --> &xt[i].mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&xt[i].mutex);
                               lock(sk_lock-AF_INET6);
                               lock(&xt[i].mutex);
  lock(rtnl_mutex);

 *** DEADLOCK ***

1 lock held by syzkaller428858/4154:
 #0:  (&xt[i].mutex){+.+.}, at: [<0000000097c1c439>] xt_find_table_lock+0x3e/0x3e0 net/netfilter/x_tables.c:1041

stack backtrace:
CPU: 0 PID: 4154 Comm: syzkaller428858 Not tainted 4.15.0+ #300
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: 0033:0x44438a
RSP: 002b:00007fff404a0a08 EFLAGS: 00000206 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000006cc100 RCX: 000000000044438a
RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00000000006cc100 R08: 00000000000002d8 R09: 0000000002006880
R10: 00000000006cc528 R11: 0000000000000206 R12: 0000000000000003
R13: 00000000006cf0a8 R14: 00000000006cf050 R15: 00000000004a332e