[ OK ] Started Getty on tty2. [ OK ] Started Serial Getty on ttyS0. [ OK ] Started Getty on tty1. [ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ 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 '10.128.1.67' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 28.893833] netlink: 4 bytes leftover after parsing attributes in process `syz-executor450'. executing program [ 28.955447] netlink: 4 bytes leftover after parsing attributes in process `syz-executor450'. executing program [ 29.004785] netlink: 4 bytes leftover after parsing attributes in process `syz-executor450'. executing program [ 29.064452] netlink: 4 bytes leftover after parsing attributes in process `syz-executor450'. executing program [ 29.114358] netlink: 4 bytes leftover after parsing attributes in process `syz-executor450'. executing program [ 29.164261] netlink: 4 bytes leftover after parsing attributes in process `syz-executor450'. executing program [ 29.224446] netlink: 4 bytes leftover after parsing attributes in process `syz-executor450'. executing program [ 29.284062] netlink: 4 bytes leftover after parsing attributes in process `syz-executor450'. executing program [ 29.343943] netlink: 4 bytes leftover after parsing attributes in process `syz-executor450'. executing program [ 29.403897] netlink: 4 bytes leftover after parsing attributes in process `syz-executor450'. 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 [ 30.583507] ================================================================== [ 30.591007] BUG: KASAN: use-after-free in refcount_dec_not_one+0x9a/0xc0 [ 30.597855] Read of size 4 at addr ffff8880a1966158 by task syz-executor450/8172 [ 30.605378] [ 30.606987] CPU: 0 PID: 8172 Comm: syz-executor450 Not tainted 4.14.225-syzkaller #0 [ 30.614864] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.624217] Call Trace: [ 30.626814] dump_stack+0x1b2/0x281 [ 30.630456] print_address_description.cold+0x54/0x1d3 [ 30.635726] kasan_report_error.cold+0x8a/0x191 [ 30.640409] ? refcount_dec_not_one+0x9a/0xc0 [ 30.644909] __asan_report_load4_noabort+0x68/0x70 [ 30.649830] ? refcount_dec_not_one+0x9a/0xc0 [ 30.654332] refcount_dec_not_one+0x9a/0xc0 [ 30.658644] refcount_dec_and_mutex_lock+0x1a/0x60 [ 30.663647] nbd_genl_connect+0xf94/0x1400 [ 30.667888] ? nbd_xmit_timeout+0x500/0x500 [ 30.672196] ? validate_nla+0x192/0x5e0 [ 30.676158] genl_family_rcv_msg+0x572/0xb20 [ 30.680643] ? genl_rcv+0x40/0x40 [ 30.684089] ? __ww_mutex_wakeup_for_backoff+0x210/0x210 [ 30.689527] ? trace_hardirqs_on+0x10/0x10 [ 30.693748] ? sock_sendmsg+0xb5/0x100 [ 30.697623] genl_rcv_msg+0xaf/0x140 [ 30.701344] netlink_rcv_skb+0x125/0x390 [ 30.705401] ? genl_family_rcv_msg+0xb20/0xb20 [ 30.709987] ? netlink_ack+0x9a0/0x9a0 [ 30.713867] ? lock_acquire+0x170/0x3f0 [ 30.717839] genl_rcv+0x24/0x40 [ 30.721192] netlink_unicast+0x437/0x610 [ 30.725341] ? netlink_sendskb+0xd0/0xd0 [ 30.729400] ? __check_object_size+0x179/0x230 [ 30.734237] netlink_sendmsg+0x62e/0xb80 [ 30.738293] ? nlmsg_notify+0x170/0x170 [ 30.742278] ? kernel_recvmsg+0x210/0x210 [ 30.746411] ? security_socket_sendmsg+0x83/0xb0 [ 30.751150] ? nlmsg_notify+0x170/0x170 [ 30.755109] sock_sendmsg+0xb5/0x100 [ 30.758818] ___sys_sendmsg+0x6c8/0x800 [ 30.762800] ? copy_msghdr_from_user+0x3b0/0x3b0 [ 30.767562] ? netlink_dump+0xad0/0xad0 [ 30.771531] ? nlmsg_notify+0x170/0x170 [ 30.775584] ? security_socket_recvmsg+0x8b/0xc0 [ 30.780322] ? SyS_recvfrom+0x27f/0x340 [ 30.784292] ? SyS_send+0x40/0x40 [ 30.787750] ? __fdget+0x167/0x1f0 [ 30.791269] ? sockfd_lookup_light+0xb2/0x160 [ 30.795756] __sys_sendmsg+0xa3/0x120 [ 30.799553] ? SyS_shutdown+0x160/0x160 [ 30.803510] ? up_read+0x17/0x30 [ 30.806859] ? __do_page_fault+0x159/0xad0 [ 30.811093] SyS_sendmsg+0x27/0x40 [ 30.814618] ? __sys_sendmsg+0x120/0x120 [ 30.818683] do_syscall_64+0x1d5/0x640 [ 30.822571] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 30.827744] RIP: 0033:0x440739 [ 30.830912] RSP: 002b:00007ffd54387e68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 30.838706] RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 0000000000440739 [ 30.845961] RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000003 [ 30.853234] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001 [ 30.860492] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000075fb [ 30.868110] R13: 00007ffd54387e7c R14: 00007ffd54387e90 R15: 00007ffd54387e80 [ 30.875483] [ 30.877105] Allocated by task 8158: [ 30.880724] kasan_kmalloc+0xeb/0x160 [ 30.884535] kmem_cache_alloc_trace+0x131/0x3d0 [ 30.889192] nbd_dev_add+0x7c/0x800 [ 30.892802] nbd_genl_connect+0x3a4/0x1400 [ 30.897033] genl_family_rcv_msg+0x572/0xb20 [ 30.901423] genl_rcv_msg+0xaf/0x140 [ 30.905212] netlink_rcv_skb+0x125/0x390 [ 30.909266] genl_rcv+0x24/0x40 [ 30.912525] netlink_unicast+0x437/0x610 [ 30.916594] netlink_sendmsg+0x62e/0xb80 [ 30.920638] sock_sendmsg+0xb5/0x100 [ 30.925294] ___sys_sendmsg+0x6c8/0x800 [ 30.929272] __sys_sendmsg+0xa3/0x120 [ 30.933143] SyS_sendmsg+0x27/0x40 [ 30.936691] do_syscall_64+0x1d5/0x640 [ 30.940560] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 30.945740] [ 30.947366] Freed by task 8172: [ 30.950680] kasan_slab_free+0xc3/0x1a0 [ 30.954640] kfree+0xc9/0x250 [ 30.957753] nbd_put.part.0+0x100/0x140 [ 30.962436] nbd_config_put+0x62a/0x810 [ 30.966410] nbd_genl_connect+0xf6c/0x1400 [ 30.971417] genl_family_rcv_msg+0x572/0xb20 [ 30.975814] genl_rcv_msg+0xaf/0x140 [ 30.979596] netlink_rcv_skb+0x125/0x390 [ 30.983663] genl_rcv+0x24/0x40 [ 30.987459] netlink_unicast+0x437/0x610 [ 30.991514] netlink_sendmsg+0x62e/0xb80 [ 30.995599] sock_sendmsg+0xb5/0x100 [ 30.999313] ___sys_sendmsg+0x6c8/0x800 [ 31.003366] __sys_sendmsg+0xa3/0x120 [ 31.007166] SyS_sendmsg+0x27/0x40 [ 31.015049] do_syscall_64+0x1d5/0x640 [ 31.018926] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 31.024114] [ 31.025741] The buggy address belongs to the object at ffff8880a1966080 [ 31.025741] which belongs to the cache kmalloc-512 of size 512 [ 31.038409] The buggy address is located 216 bytes inside of [ 31.038409] 512-byte region [ffff8880a1966080, ffff8880a1966280) [ 31.050261] The buggy address belongs to the page: [ 31.055197] page:ffffea0002865980 count:1 mapcount:0 mapping:ffff8880a1966080 index:0x0 [ 31.063345] flags: 0xfff00000000100(slab) [ 31.067611] raw: 00fff00000000100 ffff8880a1966080 0000000000000000 0000000100000006 [ 31.075498] raw: ffffea00028de7a0 ffffea000288fee0 ffff88813fe80940 0000000000000000 [ 31.083361] page dumped because: kasan: bad access detected [ 31.089073] [ 31.090685] Memory state around the buggy address: [ 31.095621] ffff8880a1966000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 31.102981] ffff8880a1966080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 31.110345] >ffff8880a1966100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 31.117747] ^ [ 31.124079] ffff8880a1966180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 31.131686] ffff8880a1966200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 31.139024] ================================================================== [ 31.146461] Disabling lock debugging due to kernel taint [ 31.155969] Kernel panic - not syncing: panic_on_warn set ... [ 31.155969] [ 31.163341] CPU: 0 PID: 8172 Comm: syz-executor450 Tainted: G B 4.14.225-syzkaller #0 [ 31.172437] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.181792] Call Trace: [ 31.184381] dump_stack+0x1b2/0x281 [ 31.188013] panic+0x1f9/0x42d [ 31.191209] ? add_taint.cold+0x16/0x16 [ 31.195177] ? ___preempt_schedule+0x16/0x18 [ 31.199663] kasan_end_report+0x43/0x49 [ 31.203641] kasan_report_error.cold+0xa7/0x191 [ 31.208596] ? refcount_dec_not_one+0x9a/0xc0 [ 31.213093] __asan_report_load4_noabort+0x68/0x70 [ 31.218006] ? refcount_dec_not_one+0x9a/0xc0 [ 31.222500] refcount_dec_not_one+0x9a/0xc0 [ 31.226838] refcount_dec_and_mutex_lock+0x1a/0x60 [ 31.231759] nbd_genl_connect+0xf94/0x1400 [ 31.236100] ? nbd_xmit_timeout+0x500/0x500 [ 31.240418] ? validate_nla+0x192/0x5e0 [ 31.244380] genl_family_rcv_msg+0x572/0xb20 [ 31.248960] ? genl_rcv+0x40/0x40 [ 31.252395] ? __ww_mutex_wakeup_for_backoff+0x210/0x210 [ 31.257824] ? trace_hardirqs_on+0x10/0x10 [ 31.262052] ? sock_sendmsg+0xb5/0x100 [ 31.265921] genl_rcv_msg+0xaf/0x140 [ 31.269618] netlink_rcv_skb+0x125/0x390 [ 31.273661] ? genl_family_rcv_msg+0xb20/0xb20 [ 31.278223] ? netlink_ack+0x9a0/0x9a0 [ 31.282091] ? lock_acquire+0x170/0x3f0 [ 31.286055] genl_rcv+0x24/0x40 [ 31.289349] netlink_unicast+0x437/0x610 [ 31.293399] ? netlink_sendskb+0xd0/0xd0 [ 31.297438] ? __check_object_size+0x179/0x230 [ 31.302022] netlink_sendmsg+0x62e/0xb80 [ 31.306238] ? nlmsg_notify+0x170/0x170 [ 31.310191] ? kernel_recvmsg+0x210/0x210 [ 31.314331] ? security_socket_sendmsg+0x83/0xb0 [ 31.319085] ? nlmsg_notify+0x170/0x170 [ 31.323046] sock_sendmsg+0xb5/0x100 [ 31.326739] ___sys_sendmsg+0x6c8/0x800 [ 31.330691] ? copy_msghdr_from_user+0x3b0/0x3b0 [ 31.335427] ? netlink_dump+0xad0/0xad0 [ 31.339395] ? nlmsg_notify+0x170/0x170 [ 31.343372] ? security_socket_recvmsg+0x8b/0xc0 [ 31.348123] ? SyS_recvfrom+0x27f/0x340 [ 31.352076] ? SyS_send+0x40/0x40 [ 31.355516] ? __fdget+0x167/0x1f0 [ 31.359034] ? sockfd_lookup_light+0xb2/0x160 [ 31.363512] __sys_sendmsg+0xa3/0x120 [ 31.367297] ? SyS_shutdown+0x160/0x160 [ 31.371279] ? up_read+0x17/0x30 [ 31.374643] ? __do_page_fault+0x159/0xad0 [ 31.378861] SyS_sendmsg+0x27/0x40 [ 31.382381] ? __sys_sendmsg+0x120/0x120 [ 31.386437] do_syscall_64+0x1d5/0x640 [ 31.390324] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 31.395602] RIP: 0033:0x440739 [ 31.398785] RSP: 002b:00007ffd54387e68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 31.406471] RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 0000000000440739 [ 31.413727] RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000003 [ 31.421114] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001 [ 31.428374] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000075fb [ 31.435634] R13: 00007ffd54387e7c R14: 00007ffd54387e90 R15: 00007ffd54387e80 [ 31.443447] Kernel Offset: disabled [ 31.447062] Rebooting in 86400 seconds..