[ 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. [ OK ] Listening on Load/Save RF Kill Switch Status /dev/rfkill Watch. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.15' (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 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: [ 31.570898] ================================================================== [ 31.578358] BUG: KASAN: use-after-free in refcount_dec_not_one+0x9a/0xc0 [ 31.585184] Read of size 4 at addr ffff8880a2ba20d8 by task syz-executor305/8524 [ 31.592691] [ 31.594310] CPU: 1 PID: 8524 Comm: syz-executor305 Not tainted 4.14.278-syzkaller #0 [ 31.602164] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.611494] Call Trace: [ 31.614062] dump_stack+0x1b2/0x281 [ 31.617668] print_address_description.cold+0x54/0x1d3 [ 31.622922] kasan_report_error.cold+0x8a/0x191 [ 31.627573] ? refcount_dec_not_one+0x9a/0xc0 [ 31.632046] __asan_report_load4_noabort+0x68/0x70 [ 31.636960] ? refcount_dec_not_one+0x9a/0xc0 [ 31.641432] refcount_dec_not_one+0x9a/0xc0 [ 31.645733] refcount_dec_and_mutex_lock+0x1a/0x60 [ 31.650641] nbd_genl_connect+0xf94/0x1400 [ 31.654861] ? nbd_xmit_timeout+0x500/0x500 [ 31.659170] ? validate_nla+0x192/0x5e0 [ 31.663123] ? nla_parse+0x157/0x1f0 [ 31.666814] genl_family_rcv_msg+0x572/0xb20 [ 31.671203] ? genl_rcv+0x40/0x40 [ 31.674633] ? __ww_mutex_wakeup_for_backoff+0x210/0x210 [ 31.680060] ? __kmalloc_node_track_caller+0x4c/0x70 [ 31.685139] ? trace_hardirqs_on+0x10/0x10 [ 31.689354] genl_rcv_msg+0xaf/0x140 [ 31.693046] netlink_rcv_skb+0x125/0x390 [ 31.697082] ? genl_family_rcv_msg+0xb20/0xb20 [ 31.701660] ? netlink_ack+0x9a0/0x9a0 [ 31.705528] ? lock_acquire+0x170/0x3f0 [ 31.709485] genl_rcv+0x24/0x40 [ 31.712738] netlink_unicast+0x437/0x610 [ 31.716775] ? netlink_sendskb+0xd0/0xd0 [ 31.720816] ? __check_object_size+0x179/0x230 [ 31.725377] netlink_sendmsg+0x648/0xbc0 [ 31.729423] ? nlmsg_notify+0x1b0/0x1b0 [ 31.733388] ? kernel_recvmsg+0x210/0x210 [ 31.737513] ? security_socket_sendmsg+0x83/0xb0 [ 31.742244] ? nlmsg_notify+0x1b0/0x1b0 [ 31.746193] sock_sendmsg+0xb5/0x100 [ 31.749885] ___sys_sendmsg+0x6c8/0x800 [ 31.753974] ? copy_msghdr_from_user+0x3b0/0x3b0 [ 31.758719] ? netlink_dump+0xb90/0xb90 [ 31.762683] ? nlmsg_notify+0x1b0/0x1b0 [ 31.766645] ? security_socket_recvmsg+0x8b/0xc0 [ 31.771387] ? SyS_recvfrom+0x27f/0x340 [ 31.775348] ? SyS_send+0x40/0x40 [ 31.778787] ? vm_insert_page+0x7c0/0x7c0 [ 31.782918] ? __fdget+0x167/0x1f0 [ 31.786438] ? sockfd_lookup_light+0xb2/0x160 [ 31.791032] __sys_sendmsg+0xa3/0x120 [ 31.794817] ? SyS_shutdown+0x160/0x160 [ 31.798778] ? up_read+0x17/0x30 [ 31.802131] ? __do_page_fault+0x159/0xad0 [ 31.806348] SyS_sendmsg+0x27/0x40 [ 31.809866] ? __sys_sendmsg+0x120/0x120 [ 31.813912] do_syscall_64+0x1d5/0x640 [ 31.817790] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 31.822957] RIP: 0033:0x7f7c26cc4939 [ 31.826646] RSP: 002b:00007ffe20e62718 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 31.834330] RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 00007f7c26cc4939 [ 31.841577] RDX: 0000000000000000 RSI: 0000000020000280 RDI: 0000000000000004 [ 31.848825] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001 [ 31.856074] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000007980 [ 31.863327] R13: 00007ffe20e6272c R14: 00007ffe20e62740 R15: 00007ffe20e62730 [ 31.870593] [ 31.872208] Allocated by task 8517: [ 31.875812] kasan_kmalloc+0xeb/0x160 [ 31.879601] kmem_cache_alloc_trace+0x131/0x3d0 [ 31.884272] nbd_dev_add+0x7c/0x800 [ 31.887882] nbd_genl_connect+0x3a4/0x1400 [ 31.892098] genl_family_rcv_msg+0x572/0xb20 [ 31.896491] genl_rcv_msg+0xaf/0x140 [ 31.900190] netlink_rcv_skb+0x125/0x390 [ 31.904233] genl_rcv+0x24/0x40 [ 31.907500] netlink_unicast+0x437/0x610 [ 31.911545] netlink_sendmsg+0x648/0xbc0 [ 31.915584] sock_sendmsg+0xb5/0x100 [ 31.919273] ___sys_sendmsg+0x6c8/0x800 [ 31.923231] __sys_sendmsg+0xa3/0x120 [ 31.927011] SyS_sendmsg+0x27/0x40 [ 31.931152] do_syscall_64+0x1d5/0x640 [ 31.935019] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 31.940190] [ 31.941802] Freed by task 8524: [ 31.945065] kasan_slab_free+0xc3/0x1a0 [ 31.949020] kfree+0xc9/0x250 [ 31.952109] nbd_put.part.0+0x100/0x140 [ 31.956070] nbd_config_put+0x62a/0x810 [ 31.960025] nbd_genl_connect+0xf6c/0x1400 [ 31.964243] genl_family_rcv_msg+0x572/0xb20 [ 31.968628] genl_rcv_msg+0xaf/0x140 [ 31.972381] netlink_rcv_skb+0x125/0x390 [ 31.976421] genl_rcv+0x24/0x40 [ 31.979678] netlink_unicast+0x437/0x610 [ 31.983713] netlink_sendmsg+0x648/0xbc0 [ 31.987753] sock_sendmsg+0xb5/0x100 [ 31.991444] ___sys_sendmsg+0x6c8/0x800 [ 31.995392] __sys_sendmsg+0xa3/0x120 [ 31.999170] SyS_sendmsg+0x27/0x40 [ 32.002709] do_syscall_64+0x1d5/0x640 [ 32.006580] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 32.011749] [ 32.013355] The buggy address belongs to the object at ffff8880a2ba2000 [ 32.013355] which belongs to the cache kmalloc-512 of size 512 [ 32.025986] The buggy address is located 216 bytes inside of [ 32.025986] 512-byte region [ffff8880a2ba2000, ffff8880a2ba2200) [ 32.037831] The buggy address belongs to the page: [ 32.042745] page:ffffea00028ae880 count:1 mapcount:0 mapping:ffff8880a2ba2000 index:0xffff8880a2ba2280 [ 32.052164] flags: 0xfff00000000100(slab) [ 32.056287] raw: 00fff00000000100 ffff8880a2ba2000 ffff8880a2ba2280 0000000100000005 [ 32.064151] raw: ffffea00028c5e60 ffffea00024f4fa0 ffff88813fe74940 0000000000000000 [ 32.072011] page dumped because: kasan: bad access detected [ 32.077704] [ 32.079316] Memory state around the buggy address: [ 32.084224] ffff8880a2ba1f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 32.091558] ffff8880a2ba2000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 32.099019] >ffff8880a2ba2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 32.106463] ^ [ 32.112769] ffff8880a2ba2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 32.120115] ffff8880a2ba2180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 32.127730] ================================================================== [ 32.135066] Disabling lock debugging due to kernel taint [ 32.144255] Kernel panic - not syncing: panic_on_warn set ... [ 32.144255] [ 32.151614] CPU: 1 PID: 8524 Comm: syz-executor305 Tainted: G B 4.14.278-syzkaller #0 [ 32.160693] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 32.170036] Call Trace: [ 32.172612] dump_stack+0x1b2/0x281 [ 32.176231] panic+0x1f9/0x42d [ 32.179490] ? add_taint.cold+0x16/0x16 [ 32.183535] ? ___preempt_schedule+0x16/0x18 [ 32.188028] kasan_end_report+0x43/0x49 [ 32.191980] kasan_report_error.cold+0xa7/0x191 [ 32.196631] ? refcount_dec_not_one+0x9a/0xc0 [ 32.201100] __asan_report_load4_noabort+0x68/0x70 [ 32.206012] ? refcount_dec_not_one+0x9a/0xc0 [ 32.210495] refcount_dec_not_one+0x9a/0xc0 [ 32.214802] refcount_dec_and_mutex_lock+0x1a/0x60 [ 32.219711] nbd_genl_connect+0xf94/0x1400 [ 32.223924] ? nbd_xmit_timeout+0x500/0x500 [ 32.228227] ? validate_nla+0x192/0x5e0 [ 32.232177] ? nla_parse+0x157/0x1f0 [ 32.235870] genl_family_rcv_msg+0x572/0xb20 [ 32.240257] ? genl_rcv+0x40/0x40 [ 32.243686] ? __ww_mutex_wakeup_for_backoff+0x210/0x210 [ 32.249115] ? __kmalloc_node_track_caller+0x4c/0x70 [ 32.254195] ? trace_hardirqs_on+0x10/0x10 [ 32.258406] genl_rcv_msg+0xaf/0x140 [ 32.262092] netlink_rcv_skb+0x125/0x390 [ 32.266147] ? genl_family_rcv_msg+0xb20/0xb20 [ 32.270711] ? netlink_ack+0x9a0/0x9a0 [ 32.274573] ? lock_acquire+0x170/0x3f0 [ 32.278533] genl_rcv+0x24/0x40 [ 32.281791] netlink_unicast+0x437/0x610 [ 32.285831] ? netlink_sendskb+0xd0/0xd0 [ 32.289878] ? __check_object_size+0x179/0x230 [ 32.294435] netlink_sendmsg+0x648/0xbc0 [ 32.298488] ? nlmsg_notify+0x1b0/0x1b0 [ 32.302450] ? kernel_recvmsg+0x210/0x210 [ 32.306587] ? security_socket_sendmsg+0x83/0xb0 [ 32.311335] ? nlmsg_notify+0x1b0/0x1b0 [ 32.315298] sock_sendmsg+0xb5/0x100 [ 32.319163] ___sys_sendmsg+0x6c8/0x800 [ 32.323198] ? copy_msghdr_from_user+0x3b0/0x3b0 [ 32.327938] ? netlink_dump+0xb90/0xb90 [ 32.331888] ? nlmsg_notify+0x1b0/0x1b0 [ 32.335836] ? security_socket_recvmsg+0x8b/0xc0 [ 32.340566] ? SyS_recvfrom+0x27f/0x340 [ 32.344512] ? SyS_send+0x40/0x40 [ 32.347958] ? vm_insert_page+0x7c0/0x7c0 [ 32.352080] ? __fdget+0x167/0x1f0 [ 32.355594] ? sockfd_lookup_light+0xb2/0x160 [ 32.360061] __sys_sendmsg+0xa3/0x120 [ 32.363836] ? SyS_shutdown+0x160/0x160 [ 32.367788] ? up_read+0x17/0x30 [ 32.371127] ? __do_page_fault+0x159/0xad0 [ 32.375334] SyS_sendmsg+0x27/0x40 [ 32.378850] ? __sys_sendmsg+0x120/0x120 [ 32.382884] do_syscall_64+0x1d5/0x640 [ 32.386749] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 32.391915] RIP: 0033:0x7f7c26cc4939 [ 32.395596] RSP: 002b:00007ffe20e62718 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 32.407798] RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 00007f7c26cc4939 [ 32.415045] RDX: 0000000000000000 RSI: 0000000020000280 RDI: 0000000000000004 [ 32.422289] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001 [ 32.429536] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000007980 [ 32.436782] R13: 00007ffe20e6272c R14: 00007ffe20e62740 R15: 00007ffe20e62730 [ 32.444104] Kernel Offset: disabled [ 32.447711] Rebooting in 86400 seconds..