[ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Starting Load/Save RF Kill Switch Status... [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.1.21' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 36.863020] ================================================================== [ 36.870966] BUG: KASAN: use-after-free in refcount_dec_not_one+0x9a/0xc0 [ 36.878027] Read of size 4 at addr ffff8880b1b3eb98 by task syz-executor298/8412 [ 36.885749] [ 36.887368] CPU: 1 PID: 8412 Comm: syz-executor298 Not tainted 4.14.224-syzkaller #0 [ 36.895525] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 36.905010] Call Trace: [ 36.907615] dump_stack+0x1b2/0x281 [ 36.911250] print_address_description.cold+0x54/0x1d3 [ 36.916521] kasan_report_error.cold+0x8a/0x191 [ 36.921184] ? refcount_dec_not_one+0x9a/0xc0 [ 36.925719] __asan_report_load4_noabort+0x68/0x70 [ 36.930641] ? refcount_dec_not_one+0x9a/0xc0 [ 36.935319] refcount_dec_not_one+0x9a/0xc0 [ 36.939651] refcount_dec_and_mutex_lock+0x1a/0x60 [ 36.944641] nbd_genl_connect+0xf94/0x1400 [ 36.948872] ? nbd_xmit_timeout+0x500/0x500 [ 36.953202] ? validate_nla+0x192/0x5e0 [ 36.957400] ? nla_parse+0x157/0x1f0 [ 36.961549] genl_family_rcv_msg+0x572/0xb20 [ 36.966185] ? genl_rcv+0x40/0x40 [ 36.969949] ? __ww_mutex_wakeup_for_backoff+0x210/0x210 [ 36.975505] ? trace_hardirqs_on+0x10/0x10 [ 36.979852] ? sock_sendmsg+0xb5/0x100 [ 36.983741] genl_rcv_msg+0xaf/0x140 [ 36.987504] netlink_rcv_skb+0x125/0x390 [ 36.991638] ? genl_family_rcv_msg+0xb20/0xb20 [ 36.996360] ? netlink_ack+0x9a0/0x9a0 [ 37.000483] ? lock_acquire+0x170/0x3f0 [ 37.004505] genl_rcv+0x24/0x40 [ 37.007926] netlink_unicast+0x437/0x610 [ 37.012027] ? netlink_sendskb+0xd0/0xd0 [ 37.016090] ? __check_object_size+0x179/0x230 [ 37.020684] netlink_sendmsg+0x62e/0xb80 [ 37.024742] ? nlmsg_notify+0x170/0x170 [ 37.028818] ? kernel_recvmsg+0x210/0x210 [ 37.033076] ? security_socket_sendmsg+0x83/0xb0 [ 37.037942] ? nlmsg_notify+0x170/0x170 [ 37.041963] sock_sendmsg+0xb5/0x100 [ 37.045673] ___sys_sendmsg+0x6c8/0x800 [ 37.049744] ? copy_msghdr_from_user+0x3b0/0x3b0 [ 37.054496] ? netlink_dump+0xad0/0xad0 [ 37.058485] ? nlmsg_notify+0x170/0x170 [ 37.062459] ? security_socket_recvmsg+0x8b/0xc0 [ 37.067231] ? SyS_recvfrom+0x27f/0x340 [ 37.071237] ? SyS_send+0x40/0x40 [ 37.074693] ? __fdget+0x167/0x1f0 [ 37.078229] ? sockfd_lookup_light+0xb2/0x160 [ 37.082929] __sys_sendmsg+0xa3/0x120 [ 37.087123] ? SyS_shutdown+0x160/0x160 [ 37.091274] ? up_read+0x17/0x30 [ 37.094642] ? __do_page_fault+0x159/0xad0 [ 37.098994] SyS_sendmsg+0x27/0x40 [ 37.102560] ? __sys_sendmsg+0x120/0x120 [ 37.106612] do_syscall_64+0x1d5/0x640 [ 37.110520] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 37.115827] RIP: 0033:0x4407b9 [ 37.119002] RSP: 002b:00007ffebce76778 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 37.126785] RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 00000000004407b9 [ 37.134264] RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000003 [ 37.141969] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001 [ 37.149332] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000008e70 [ 37.156595] R13: 00007ffebce7678c R14: 00007ffebce767a0 R15: 00007ffebce76790 [ 37.163951] [ 37.165580] Allocated by task 8405: [ 37.169214] kasan_kmalloc+0xeb/0x160 [ 37.173008] kmem_cache_alloc_trace+0x131/0x3d0 [ 37.177663] nbd_dev_add+0x7c/0x800 [ 37.181392] nbd_genl_connect+0x3a4/0x1400 [ 37.186152] genl_family_rcv_msg+0x572/0xb20 [ 37.190742] genl_rcv_msg+0xaf/0x140 [ 37.194443] netlink_rcv_skb+0x125/0x390 [ 37.198505] genl_rcv+0x24/0x40 [ 37.201939] netlink_unicast+0x437/0x610 [ 37.206004] netlink_sendmsg+0x62e/0xb80 [ 37.210066] sock_sendmsg+0xb5/0x100 [ 37.213860] ___sys_sendmsg+0x6c8/0x800 [ 37.217822] __sys_sendmsg+0xa3/0x120 [ 37.221607] SyS_sendmsg+0x27/0x40 [ 37.225160] do_syscall_64+0x1d5/0x640 [ 37.229051] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 37.234234] [ 37.235843] Freed by task 8412: [ 37.239306] kasan_slab_free+0xc3/0x1a0 [ 37.243456] kfree+0xc9/0x250 [ 37.246917] nbd_put.part.0+0x100/0x140 [ 37.250875] nbd_config_put+0x62a/0x810 [ 37.254936] nbd_genl_connect+0xf6c/0x1400 [ 37.259164] genl_family_rcv_msg+0x572/0xb20 [ 37.263595] genl_rcv_msg+0xaf/0x140 [ 37.267298] netlink_rcv_skb+0x125/0x390 [ 37.271604] genl_rcv+0x24/0x40 [ 37.274879] netlink_unicast+0x437/0x610 [ 37.279468] netlink_sendmsg+0x62e/0xb80 [ 37.283535] sock_sendmsg+0xb5/0x100 [ 37.287256] ___sys_sendmsg+0x6c8/0x800 [ 37.292250] __sys_sendmsg+0xa3/0x120 [ 37.296156] SyS_sendmsg+0x27/0x40 [ 37.299846] do_syscall_64+0x1d5/0x640 [ 37.303735] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 37.309042] [ 37.310696] The buggy address belongs to the object at ffff8880b1b3eac0 [ 37.310696] which belongs to the cache kmalloc-512 of size 512 [ 37.323522] The buggy address is located 216 bytes inside of [ 37.323522] 512-byte region [ffff8880b1b3eac0, ffff8880b1b3ecc0) [ 37.336146] The buggy address belongs to the page: [ 37.341293] page:ffffea0002c6cf80 count:1 mapcount:0 mapping:ffff8880b1b3e0c0 index:0x0 [ 37.349600] flags: 0xfff00000000100(slab) [ 37.353883] raw: 00fff00000000100 ffff8880b1b3e0c0 0000000000000000 0000000100000006 [ 37.361771] raw: ffffea0002a4bea0 ffffea0002cac760 ffff88813fe80940 0000000000000000 [ 37.369701] page dumped because: kasan: bad access detected [ 37.375399] [ 37.377010] Memory state around the buggy address: [ 37.381926] ffff8880b1b3ea80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb [ 37.389279] ffff8880b1b3eb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 37.396633] >ffff8880b1b3eb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 37.404017] ^ [ 37.408158] ffff8880b1b3ec00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 37.415859] ffff8880b1b3ec80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc [ 37.423232] ================================================================== [ 37.430859] Disabling lock debugging due to kernel taint [ 37.437679] Kernel panic - not syncing: panic_on_warn set ... [ 37.437679] [ 37.445078] CPU: 1 PID: 8412 Comm: syz-executor298 Tainted: G B 4.14.224-syzkaller #0 [ 37.454265] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 37.463657] Call Trace: [ 37.466266] dump_stack+0x1b2/0x281 [ 37.469992] panic+0x1f9/0x42d [ 37.473205] ? add_taint.cold+0x16/0x16 [ 37.477231] ? ___preempt_schedule+0x16/0x18 [ 37.481646] kasan_end_report+0x43/0x49 [ 37.486149] kasan_report_error.cold+0xa7/0x191 [ 37.490882] ? refcount_dec_not_one+0x9a/0xc0 [ 37.495390] __asan_report_load4_noabort+0x68/0x70 [ 37.500455] ? refcount_dec_not_one+0x9a/0xc0 [ 37.504944] refcount_dec_not_one+0x9a/0xc0 [ 37.509418] refcount_dec_and_mutex_lock+0x1a/0x60 [ 37.514355] nbd_genl_connect+0xf94/0x1400 [ 37.518859] ? nbd_xmit_timeout+0x500/0x500 [ 37.523421] ? validate_nla+0x192/0x5e0 [ 37.527598] ? nla_parse+0x157/0x1f0 [ 37.531315] genl_family_rcv_msg+0x572/0xb20 [ 37.536248] ? genl_rcv+0x40/0x40 [ 37.539695] ? __ww_mutex_wakeup_for_backoff+0x210/0x210 [ 37.545315] ? trace_hardirqs_on+0x10/0x10 [ 37.549664] ? sock_sendmsg+0xb5/0x100 [ 37.553556] genl_rcv_msg+0xaf/0x140 [ 37.557288] netlink_rcv_skb+0x125/0x390 [ 37.561343] ? genl_family_rcv_msg+0xb20/0xb20 [ 37.566036] ? netlink_ack+0x9a0/0x9a0 [ 37.570024] ? lock_acquire+0x170/0x3f0 [ 37.574077] genl_rcv+0x24/0x40 [ 37.577446] netlink_unicast+0x437/0x610 [ 37.581515] ? netlink_sendskb+0xd0/0xd0 [ 37.585677] ? __check_object_size+0x179/0x230 [ 37.590253] netlink_sendmsg+0x62e/0xb80 [ 37.594321] ? nlmsg_notify+0x170/0x170 [ 37.598285] ? kernel_recvmsg+0x210/0x210 [ 37.602524] ? security_socket_sendmsg+0x83/0xb0 [ 37.607561] ? nlmsg_notify+0x170/0x170 [ 37.611538] sock_sendmsg+0xb5/0x100 [ 37.615378] ___sys_sendmsg+0x6c8/0x800 [ 37.619523] ? copy_msghdr_from_user+0x3b0/0x3b0 [ 37.624360] ? netlink_dump+0xad0/0xad0 [ 37.628325] ? nlmsg_notify+0x170/0x170 [ 37.632508] ? security_socket_recvmsg+0x8b/0xc0 [ 37.637763] ? SyS_recvfrom+0x27f/0x340 [ 37.641731] ? SyS_send+0x40/0x40 [ 37.645168] ? __fdget+0x167/0x1f0 [ 37.648808] ? sockfd_lookup_light+0xb2/0x160 [ 37.653419] __sys_sendmsg+0xa3/0x120 [ 37.657218] ? SyS_shutdown+0x160/0x160 [ 37.661310] ? up_read+0x17/0x30 [ 37.665098] ? __do_page_fault+0x159/0xad0 [ 37.669326] SyS_sendmsg+0x27/0x40 [ 37.672956] ? __sys_sendmsg+0x120/0x120 [ 37.677023] do_syscall_64+0x1d5/0x640 [ 37.681076] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 37.686253] RIP: 0033:0x4407b9 [ 37.689434] RSP: 002b:00007ffebce76778 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 37.697291] RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 00000000004407b9 [ 37.704638] RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000003 [ 37.712215] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001 [ 37.719993] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000008e70 [ 37.727263] R13: 00007ffebce7678c R14: 00007ffebce767a0 R15: 00007ffebce76790 [ 37.735910] Kernel Offset: disabled [ 37.739671] Rebooting in 86400 seconds..