syzbot

audit: type=1400 audit(1517459985.254:7): avc:  denied  { map } for  pid=4164 comm="syzkaller437415" path="/root/syzkaller437415992" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1

======================================================
WARNING: possible circular locking dependency detected
4.15.0+ #290 Not tainted
------------------------------------------------------
syzkaller437415/4164 is trying to acquire lock:
 (sk_lock-AF_INET){+.+.}, at: [<00000000e7c7df27>] lock_sock include/net/sock.h:1461 [inline]
 (sk_lock-AF_INET){+.+.}, at: [<00000000e7c7df27>] do_ip_setsockopt.isra.12+0x1d9/0x3210 net/ipv4/ip_sockglue.c:646

but task is already holding lock:
 (rtnl_mutex){+.+.}, at: [<00000000792bd739>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (rtnl_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
       rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74
       register_netdevice_notifier+0xad/0x860 net/core/dev.c:1607
       tee_tg_check+0x1a0/0x280 net/netfilter/xt_TEE.c:106
       xt_check_target+0x22c/0x7d0 net/netfilter/x_tables.c:845
       check_target net/ipv4/netfilter/ip_tables.c:513 [inline]
       find_check_entry.isra.8+0x8c8/0xcb0 net/ipv4/netfilter/ip_tables.c:554
       translate_table+0xed1/0x1610 net/ipv4/netfilter/ip_tables.c:725
       do_replace net/ipv4/netfilter/ip_tables.c:1141 [inline]
       do_ipt_set_ctl+0x370/0x5f0 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+0xa1/0xb0 net/ipv4/ip_sockglue.c:1260
       raw_setsockopt+0xb7/0xd0 net/ipv4/raw.c:870
       sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2978
       SYSC_setsockopt net/socket.c:1849 [inline]
       SyS_setsockopt+0x189/0x360 net/socket.c:1828
       entry_SYSCALL_64_fastpath+0x29/0xa0

-> #0 (sk_lock-AF_INET){+.+.}:
       lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
       lock_sock_nested+0xc2/0x110 net/core/sock.c:2780
       lock_sock include/net/sock.h:1461 [inline]
       do_ip_setsockopt.isra.12+0x1d9/0x3210 net/ipv4/ip_sockglue.c:646
       ip_setsockopt+0x3a/0xb0 net/ipv4/ip_sockglue.c:1252
       udp_setsockopt+0x45/0x80 net/ipv4/udp.c:2401
       sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2978
       SYSC_setsockopt net/socket.c:1849 [inline]
       SyS_setsockopt+0x189/0x360 net/socket.c:1828
       entry_SYSCALL_64_fastpath+0x29/0xa0

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(rtnl_mutex);
                               lock(sk_lock-AF_INET);
                               lock(rtnl_mutex);
  lock(sk_lock-AF_INET);

 *** DEADLOCK ***

1 lock held by syzkaller437415/4164:
 #0:  (rtnl_mutex){+.+.}, at: [<00000000792bd739>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74

stack backtrace:
CPU: 0 PID: 4164 Comm: syzkaller437415 Not tainted 4.15.0+ #290
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
 lock_sock_nested+0xc2/0x110 net/core/sock.c:2780
 lock_sock include/net/sock.h:1461 [inline]
 do_ip_setsockopt.isra.12+0x1d9/0x3210 net/ipv4/ip_sockglue.c:646
 ip_setsockopt+0x3a/0xb0 net/ipv4/ip_sockglue.c:1252
 udp_setsockopt+0x45/0x80 net/ipv4/udp.c:2401
 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2978
 SYSC_setsockopt net/socket.c:1849 [inline]
 SyS_setsockopt+0x189/0x360 net/socket.c:1828
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x440ba9
RSP: 002b:00007ffe9a47ed48 EFLAGS: 00000207 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: ffffffffffffffff RCX: 0000000000440ba9
RDX: 0000000000000027 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00000000006cb018 R08: 000000000000000c R09: 0000000000000000
R10: 0000000020e48000 R11: 0000000000000207 R12: 00000