audit: type=1400 audit(1518364015.690:10): avc: denied { sys_chroot } for pid=4120 comm="syzkaller251109" capability=18 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 ===================================== WARNING: bad unlock balance detected! 4.15.0+ #222 Not tainted ------------------------------------- syzkaller251109/4120 is trying to release lock (rcu_read_lock_bh) at: [] rcu_read_unlock_bh include/linux/rcupdate.h:722 [inline] [] hashlimit_mt_common.isra.10+0x1beb/0x2610 net/netfilter/xt_hashlimit.c:777 but there are no more locks to release! other info that might help us debug this: 3 locks held by syzkaller251109/4120: #0: (sk_lock-AF_INET6){+.+.}, at: [<00000000783390c2>] lock_sock include/net/sock.h:1463 [inline] #0: (sk_lock-AF_INET6){+.+.}, at: [<00000000783390c2>] sctp_connect+0x23/0xf0 net/sctp/socket.c:4294 #1: (rcu_read_lock){....}, at: [<000000009525a442>] read_pnet include/net/net_namespace.h:280 [inline] #1: (rcu_read_lock){....}, at: [<000000009525a442>] sock_net include/net/sock.h:2305 [inline] #1: (rcu_read_lock){....}, at: [<000000009525a442>] ip_queue_xmit+0x9e/0x18e0 net/ipv4/ip_output.c:429 #2: (rcu_read_lock){....}, at: [<000000009fba0db4>] nf_hook include/linux/netfilter.h:206 [inline] #2: (rcu_read_lock){....}, at: [<000000009fba0db4>] __ip_local_out+0x29b/0xa30 net/ipv4/ip_output.c:113 stack backtrace: CPU: 1 PID: 4120 Comm: syzkaller251109 Not tainted 4.15.0+ #222 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_unlock_imbalance_bug+0x12f/0x140 kernel/locking/lockdep.c:3484 __lock_release kernel/locking/lockdep.c:3691 [inline] lock_release+0x6fe/0xa40 kernel/locking/lockdep.c:3939 rcu_lock_release include/linux/rcupdate.h:249 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:724 [inline] hashlimit_mt_common.isra.10+0x1c08/0x2610 net/netfilter/xt_hashlimit.c:777 hashlimit_mt_v2+0x496/0x710 net/netfilter/xt_hashlimit.c:837 ipt_do_table+0xa90/0x1950 net/ipv4/netfilter/ip_tables.c:296 iptable_filter_hook+0x65/0x80 net/ipv4/netfilter/iptable_filter.c:41 nf_hook_entry_hookfn include/linux/netfilter.h:120 [inline] nf_hook_slow+0xba/0x1a0 net/netfilter/core.c:483 nf_hook include/linux/netfilter.h:243 [inline] __ip_local_out+0x4c1/0xa30 net/ipv4/ip_output.c:113 ip_local_out+0x2d/0x160 net/ipv4/ip_output.c:122 ip_queue_xmit+0x8c0/0x18e0 net/ipv4/ip_output.c:504 sctp_v4_xmit+0x108/0x140 net/sctp/protocol.c:992 sctp_packet_transmit+0x225e/0x3750 net/sctp/output.c:638 sctp_outq_flush+0xabb/0x4060 net/sctp/outqueue.c:911 sctp_outq_uncork+0x5a/0x70 net/sctp/outqueue.c:776 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1807 [inline] sctp_side_effects net/sctp/sm_sideeffect.c:1210 [inline] sctp_do_sm+0x4e0/0x6ed0 net/sctp/sm_sideeffect.c:1181 sctp_primitive_ASSOCIATE+0x9d/0xd0 net/sctp/primitive.c:88 __sctp_connect+0x829/0xca0 net/sctp/socket.c:1235 sctp_connect+0xb4/0xf0 net/sctp/socket.c:4307 inet_dgram_connect+0x16b/0x1f0 net/ipv4/af_inet.c:542 SYSC_connect+0x213/0x4a0 net/socket.c:1639 SyS_connect+0x24/0x30 net/socket.c:1620 do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x26/0x9b RIP: 0033:0x44b499 RSP: 002b:00000000007efdc8