syzbot

syz-executor067[8095]: segfault at 1 ip 0000000000000001 sp 00007ffe969f2838 error 14 in syz-executor067971823[400000+1000]
syz-executor067[8116]: segfault at d ip 000000000000000d sp 00007ffe969f2880 error 14 in syz-executor067971823[400000+1000]
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
======================================================
WARNING: possible circular locking dependency detected
4.14.232-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor067/8117 is trying to acquire lock:
 (&xt[i].mutex){+.+.}, at: [<ffffffff85f095b3>] target_revfn+0x43/0x210 net/netfilter/x_tables.c:354

but task is already holding lock:
 (&table[i].mutex){+.+.}, at: [<ffffffff85e359a6>] nfnl_lock net/netfilter/nfnetlink.c:61 [inline]
 (&table[i].mutex){+.+.}, at: [<ffffffff85e359a6>] nfnetlink_rcv_msg+0x726/0xc00 net/netfilter/nfnetlink.c:209

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&table[i].mutex){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
       nf_tables_netdev_event+0x10d/0x4d0 net/netfilter/nf_tables_netdev.c:122
       notifier_call_chain+0x108/0x1a0 kernel/notifier.c:93
       call_netdevice_notifiers_info net/core/dev.c:1667 [inline]
       call_netdevice_notifiers net/core/dev.c:1683 [inline]
       rollback_registered_many+0x765/0xba0 net/core/dev.c:7203
       unregister_netdevice_many.part.0+0x18/0x2e0 net/core/dev.c:8285
       unregister_netdevice_many+0x36/0x50 net/core/dev.c:8284
       ip6gre_exit_net+0x41e/0x570 net/ipv6/ip6_gre.c:1212
       ops_exit_list+0xa5/0x150 net/core/net_namespace.c:142
       cleanup_net+0x3b3/0x840 net/core/net_namespace.c:484
       process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
       worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
       kthread+0x30d/0x420 kernel/kthread.c:232
       ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

-> #1 (rtnl_mutex){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
       unregister_netdevice_notifier+0x5e/0x2b0 net/core/dev.c:1630
       tee_tg_destroy+0x5c/0xb0 net/netfilter/xt_TEE.c:123
       cleanup_entry+0x232/0x310 net/ipv6/netfilter/ip6_tables.c:684
       __do_replace+0x38d/0x580 net/ipv6/netfilter/ip6_tables.c:1105
       do_replace net/ipv6/netfilter/ip6_tables.c:1161 [inline]
       do_ip6t_set_ctl+0x256/0x3b0 net/ipv6/netfilter/ip6_tables.c:1687
       nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
       nf_setsockopt+0x5f/0xb0 net/netfilter/nf_sockopt.c:115
       ipv6_setsockopt+0xc0/0x120 net/ipv6/ipv6_sockglue.c:937
       tcp_setsockopt+0x7b/0xc0 net/ipv4/tcp.c:2828
       SYSC_setsockopt net/socket.c:1865 [inline]
       SyS_setsockopt+0x110/0x1e0 net/socket.c:1844
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x46/0xbb

-> #0 (&xt[i].mutex){+.+.}:
       lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
       target_revfn+0x43/0x210 net/netfilter/x_tables.c:354
       xt_find_revision+0x15e/0x1d0 net/netfilter/x_tables.c:378
       nfnl_compat_get+0x1f7/0x870 net/netfilter/nft_compat.c:678
       nfnetlink_rcv_msg+0x9bb/0xc00 net/netfilter/nfnetlink.c:214
       netlink_rcv_skb+0x125/0x390 net/netlink/af_netlink.c:2433
       nfnetlink_rcv+0x1ab/0x1da0 net/netfilter/nfnetlink.c:515
       netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
       netlink_unicast+0x437/0x610 net/netlink/af_netlink.c:1313
       netlink_sendmsg+0x62e/0xb80 net/netlink/af_netlink.c:1878
       sock_sendmsg_nosec net/socket.c:646 [inline]
       sock_sendmsg+0xb5/0x100 net/socket.c:656
       ___sys_sendmsg+0x6c8/0x800 net/socket.c:2062
       __sys_sendmsg+0xa3/0x120 net/socket.c:2096
       SYSC_sendmsg net/socket.c:2107 [inline]
       SyS_sendmsg+0x27/0x40 net/socket.c:2103
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x46/0xbb

other info that might help us debug this:

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

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

1 lock held by syz-executor067/8117:
 #0:  (&table[i].mutex){+.+.}, at: [<ffffffff85e359a6>] nfnl_lock net/netfilter/nfnetlink.c:61 [inline]
 #0:  (&table[i].mutex){+.+.}, at: [<ffffffff85e359a6>] nfnetlink_rcv_msg+0x726/0xc00 net/netfilter/nfnetlink.c:209

stack backtrace:
CPU: 1 PID: 8117 Comm: syz-executor067 Not tainted 4.14.232-syzkaller #0
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+0x1b2/0x281 lib/dump_stack.c:58
 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258
 check_prev_add kernel/locking/lockdep.c:1905 [inline]
 check_prevs_add kernel/locking/lockdep.c:2022 [inline]
 validate_chain kernel/locking/lockdep.c:2464 [inline]
 __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491
 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
 __mutex_lock_common kernel/locking/mutex.c:756 [inline]
 __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
 target_revfn+0x43/0x210 net/netfilter/x_tables.c:354
 xt_find_revision+0x15e/0x1d0 net/netfilter/x_tables.c:378
 nfnl_compat_get+0x1f7/0x870 net/netfilter/nft_compat.c:678
 nfnetlink_rcv_msg+0x9bb/0xc00 net/netfilter/nfnetlink.c:214
 netlink_rcv_skb+0x125/0x390 net/netlink/af_netlink.c:2433
 nfnetlink_rcv+0x1ab/0x1da0 net/netfilter/nfnetlink.c:515
 netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
 netlink_unicast+0x437/0x610 net/netlink/af_netlink.c:1313
 netlink_sendmsg+0x62e/0xb80 net/netlink/af_netlink.c:1878
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:656
 ___sys_sendmsg+0x6c8/0x800 net/socket.c:2062
 __sys_sendmsg+0xa3/0x120 net/socket.c:2096
 SYSC_sendmsg net/socket.c:2107 [inline]
 SyS_sendmsg+0x27/0x40 net/socket.c:2103
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4402a9
RSP: 002b:00007ffe969f28c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00306e616c767069 RCX: 00000000004402a9
RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000004
RBP: 0000000000000000 R08: 00007ffe969f2a68 R09: 00007ffe969f2a68
R10: 00007ffe969f2a68 R11: 0000000000000246 R12: 00007ffe969f28dc
R13: 431bde82d7b634db R14: 00000000004ae018 R15: 0000000000400488
syz-executor067[8117]: segfault at 7ffe969f2a68 ip 00007ffe969f2a68 sp 00007ffe969f28d8 error 15
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
ip6_tables: ip6tables: counters copy to user failed while replacing table
syz-executor067[8183]: segfault at 7ffe969f2a68 ip 00007ffe969f2a68 sp 00007ffe969f28d8 error 15
IPVS: ftp: loaded support on port[0] = 21
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
syz-executor067[8272]: segfault at 7ffe969f2a68 ip 00007ffe969f2a68 sp 00007ffe969f28d8 error 15
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
syz-executor067[8296]: segfault at 7ffe969f2a68 ip 00007ffe969f2a68 sp 00007ffe969f28d8 error 15
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
syz-executor067[8406]: segfault at 7ffe969f2a68 ip 00007ffe969f2a68 sp 00007ffe969f28d8 error 15
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
syz-executor067[8430]: segfault at 7ffe969f2a68 ip 00007ffe969f2a68 sp 00007ffe969f28d8 error 15
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
syz-executor067[8453]: segfault at 7ffe969f2a68 ip 00007ffe969f2a68 sp 00007ffe969f28d8 error 15
ip6_tables: ip6tables: counters copy to user failed while replacing table
IPVS: ftp: loaded support on port[0] = 21
syz-executor067[8476]: segfault at 7ffe969f2a68 ip 00007ffe969f2a68 sp 00007ffe969f28d8 error 15