[....] Starting enhanced syslogd: rsyslogd[ 15.441842] audit: type=1400 audit(1519133341.702:5): avc: denied { syslog } for pid=3947 comm="rsyslogd" capability=34 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=capability2 permissive=1 [?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. Starting mcstransd: [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.902650] audit: type=1400 audit(1519133345.163:6): avc: denied { map } for pid=4087 comm="bash" path="/bin/bash" dev="sda1" ino=1457 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 Warning: Permanently added '10.128.0.54' (ECDSA) to the list of known hosts. net.ipv6.conf.syz0.accept_dad = 0 net.ipv6.conf.syz0.router_solicitations = 0 [ 25.244009] audit: type=1400 audit(1519133351.504:7): avc: denied { map } for pid=4101 comm="syzkaller431857" path="/root/syzkaller431857709" 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 RTNETLINK answers: Operation not supported RTNETLINK answers: No buffer space available RTNETLINK answers: Operation not supported [ 25.619463] IPv6: ADDRCONF(NETDEV_UP): bridge0: link is not ready RTNETLINK answers: Operation not supported RTNETLINK answers: Operation not supported RTNETLINK answers: Operation not supported RTNETLINK answers: Invalid argument RTNETLINK answers: Invalid argument RTNETLINK answers: Invalid argument executing program [ 25.952515] [ 25.954157] ===================================== [ 25.958965] WARNING: bad unlock balance detected! [ 25.963772] 4.16.0-rc2+ #322 Not tainted [ 25.967798] ------------------------------------- [ 25.972604] syzkaller431857/4101 is trying to release lock (rcu_read_lock_bh) at: [ 25.980201] [] hashlimit_mt_common.isra.10+0x1beb/0x2610 [ 25.987179] but there are no more locks to release! [ 25.992157] [ 25.992157] other info that might help us debug this: [ 25.998788] 3 locks held by syzkaller431857/4101: [ 26.003602] #0: (&tfile->napi_mutex){+.+.}, at: [<000000009f375a7e>] tun_get_user+0xe93/0x3810 [ 26.012500] #1: (rcu_read_lock){....}, at: [<00000000370dd5ed>] netif_receive_skb_internal+0xa2/0x670 [ 26.022008] #2: (rcu_read_lock){....}, at: [<00000000497540a1>] ipv6_rcv+0x1446/0x1fa0 [ 26.030633] [ 26.030633] stack backtrace: [ 26.035106] CPU: 0 PID: 4101 Comm: syzkaller431857 Not tainted 4.16.0-rc2+ #322 [ 26.042519] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.051844] Call Trace: [ 26.054403] dump_stack+0x194/0x257 [ 26.057999] ? arch_local_irq_restore+0x53/0x53 [ 26.062651] ? hashlimit_mt_common.isra.10+0x1beb/0x2610 [ 26.068071] print_unlock_imbalance_bug+0x12f/0x140 [ 26.073054] lock_release+0x6fe/0xa40 [ 26.076822] ? hashlimit_mt_common.isra.10+0x1beb/0x2610 [ 26.082242] ? lock_downgrade+0x980/0x980 [ 26.086360] ? lock_release+0xa40/0xa40 [ 26.090301] ? __raw_spin_lock_init+0x1c/0x100 [ 26.094850] ? do_raw_spin_trylock+0x190/0x190 [ 26.099404] hashlimit_mt_common.isra.10+0x1c08/0x2610 [ 26.104649] ? dsthash_find+0x5b0/0x5b0 [ 26.108592] ? __lock_acquire+0x664/0x3e00 [ 26.112794] ? check_noncircular+0x20/0x20 [ 26.116998] ? __put_compound_page+0xc0/0xc0 [ 26.121380] ? lock_release+0xa40/0xa40 [ 26.125321] ? __bfs+0xaa/0x750 [ 26.128571] ? bpf_prog_kallsyms_find+0xbd/0x440 [ 26.133295] ? lock_downgrade+0x980/0x980 [ 26.137410] hashlimit_mt+0x78/0x90 [ 26.141007] ? hashlimit_mt+0x78/0x90 [ 26.144782] ip6t_do_table+0x98d/0x1a30 [ 26.148722] ? is_bpf_text_address+0x7b/0x120 [ 26.153183] ? lock_downgrade+0x980/0x980 [ 26.157300] ? check_noncircular+0x20/0x20 [ 26.161510] ? ip6t_error+0x60/0x60 [ 26.165104] ? find_held_lock+0x35/0x1d0 [ 26.169134] ? check_noncircular+0x20/0x20 [ 26.173339] ? lock_acquire+0x1d5/0x580 [ 26.177279] ? lock_acquire+0x1d5/0x580 [ 26.181222] ? ipv6_rcv+0x1446/0x1fa0 [ 26.184992] ? lock_release+0xa40/0xa40 [ 26.188943] ip6table_raw_hook+0x65/0x80 [ 26.192973] nf_hook_slow+0xba/0x1a0 [ 26.196655] ipv6_rcv+0x1687/0x1fa0 [ 26.200250] ? ip6_rcv_finish+0x8c0/0x8c0 [ 26.204366] ? __lock_acquire+0x664/0x3e00 [ 26.208580] ? ip6_input+0x560/0x560 [ 26.212260] ? ip6_rcv_finish+0x8c0/0x8c0 [ 26.216378] __netif_receive_skb_core+0x1a41/0x3460 [ 26.221362] ? nf_ingress+0x9f0/0x9f0 [ 26.225136] ? __skb_flow_get_ports+0x3b0/0x420 [ 26.229775] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 26.234936] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 26.240093] ? print_irqtrace_events+0x270/0x270 [ 26.244817] ? check_noncircular+0x20/0x20 [ 26.249026] ? check_noncircular+0x20/0x20 [ 26.253229] ? lock_downgrade+0x980/0x980 [ 26.257342] ? check_noncircular+0x20/0x20 [ 26.261543] ? lock_release+0xa40/0xa40 [ 26.265486] ? is_bpf_text_address+0xa4/0x120 [ 26.269956] ? find_held_lock+0x35/0x1d0 [ 26.273993] ? print_irqtrace_events+0x270/0x270 [ 26.278719] ? netif_receive_skb_internal+0x1d7/0x670 [ 26.283876] ? lock_downgrade+0x980/0x980 [ 26.287997] ? pvclock_read_flags+0x160/0x160 [ 26.292466] ? mark_held_locks+0xaf/0x100 [ 26.296582] ? lock_acquire+0x1d5/0x580 [ 26.300524] ? lock_acquire+0x1d5/0x580 [ 26.304466] ? netif_receive_skb_internal+0xa2/0x670 [ 26.309535] ? ktime_get_with_offset+0x2c1/0x420 [ 26.314258] ? lock_release+0xa40/0xa40 [ 26.318198] ? do_gettimeofday+0x190/0x190 [ 26.322401] ? lock_release+0xa40/0xa40 [ 26.326341] __netif_receive_skb+0x2c/0x1b0 [ 26.330629] ? __netif_receive_skb+0x2c/0x1b0 [ 26.335094] netif_receive_skb_internal+0x10b/0x670 [ 26.340078] ? dev_cpu_dead+0xb00/0xb00 [ 26.344025] ? net_rx_action+0x1910/0x1910 [ 26.348236] ? eth_type_trans+0x2b2/0x710 [ 26.352350] ? eth_gro_receive+0x820/0x820 [ 26.356561] napi_gro_frags+0x58a/0xaf0 [ 26.360503] ? napi_gro_receive+0x500/0x500 [ 26.364795] ? tun_get_user+0x26f7/0x3810 [ 26.368909] tun_get_user+0x2720/0x3810 [ 26.372852] ? kernel_text_address+0x102/0x140 [ 26.377405] ? tun_build_skb.isra.50+0x1850/0x1850 [ 26.382303] ? xt_table_unlock+0x52/0x60 [ 26.386333] ? lock_downgrade+0x980/0x980 [ 26.390450] ? rawv6_setsockopt+0x4a/0xf0 [ 26.394565] ? SyS_setsockopt+0x189/0x360 [ 26.398681] ? do_syscall_64+0x280/0x940 [ 26.402711] ? tun_get+0x1ab/0x2e0 [ 26.406219] ? lock_release+0xa40/0xa40 [ 26.410161] ? __lock_is_held+0xb6/0x140 [ 26.414190] ? tun_get+0x1d4/0x2e0 [ 26.417698] ? tun_do_read+0x26c0/0x26c0 [ 26.421728] ? __check_object_size+0x8b/0x530 [ 26.426195] ? rcu_note_context_switch+0x710/0x710 [ 26.431095] tun_chr_write_iter+0xbd/0x1c0 [ 26.435297] do_iter_readv_writev+0x55c/0x830 [ 26.439762] ? vfs_dedupe_file_range+0x8f0/0x8f0 [ 26.444486] ? rw_verify_area+0xe5/0x2b0 [ 26.448517] do_iter_write+0x154/0x540 [ 26.452372] ? dup_iter+0x260/0x260 [ 26.455969] ? do_ip6t_set_ctl+0x104/0x5f0 [ 26.460172] vfs_writev+0x18a/0x340 [ 26.463767] ? vfs_iter_write+0xb0/0xb0 [ 26.467710] ? nf_setsockopt+0x93/0xc0 [ 26.471566] ? __fdget_pos+0x130/0x190 [ 26.475438] ? __fdget_raw+0x20/0x20 [ 26.479119] ? sock_common_setsockopt+0x95/0xd0 [ 26.483761] do_writev+0xfc/0x2a0 [ 26.487181] ? do_writev+0xfc/0x2a0 [ 26.490774] ? vfs_writev+0x340/0x340 [ 26.494550] ? mm_fault_error+0x2c0/0x2c0 [ 26.498666] ? move_addr_to_kernel+0x60/0x60 [ 26.503041] ? SyS_readv+0x30/0x30 [ 26.506549] SyS_writev+0x27/0x30 [ 26.509970] do_syscall_64+0x280/0x940 [ 26.513828] ? __do_page_fault+0xc90/0xc90 [ 26.518033] ? trace_event_raw_event_sys_exit+0x260/0x260 [ 26.523536] ? syscall_return_slowpath+0x550/0x550 [ 26.528432] ? syscall_return_slowpath+0x2ac/0x550 [ 26.533330] ? entry_SYSCALL_64_after_hwframe+0x52/0xb7 [ 26.538664] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 26.543475] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 26.548631] RIP: 0033:0x4461c0 [ 26.551789] RSP: 002b:00007ffdd0b33