[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.200978] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [ 16.918844] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.459647] random: sshd: uninitialized urandom read (32 bytes read) [ 17.993565] random: sshd: uninitialized urandom read (32 bytes read) [ 18.134803] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.12' (ECDSA) to the list of known hosts. [ 23.649551] random: sshd: uninitialized urandom read (32 bytes read) 2018/08/22 18:35:36 parsed 1 programs [ 24.725239] random: cc1: uninitialized urandom read (8 bytes read) 2018/08/22 18:35:37 executed programs: 0 [ 25.798807] IPVS: Creating netns size=2536 id=1 [ 25.924552] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 25.936027] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 25.980584] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 25.992265] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 26.036975] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 26.048634] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 26.061134] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 26.074990] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 26.597846] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 26.622538] IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready [ 26.628670] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready [ 26.636415] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 28.304904] l2tp_core: tunl 4: sockfd_lookup(fd=5) returned -9 [ 28.687618] ================================================================== [ 28.695005] BUG: KASAN: use-after-free in __lock_acquire+0x319b/0x4070 [ 28.701647] Read of size 8 at addr ffff8801c7d44d20 by task syz-executor0/5217 [ 28.708975] [ 28.710582] CPU: 0 PID: 5217 Comm: syz-executor0 Not tainted 4.9.123-g8dd3fc2 #79 [ 28.718179] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.727506] ffff8801bcb6fa60 ffffffff81eb9689 ffffea00071f5000 ffff8801c7d44d20 [ 28.735523] 0000000000000000 ffff8801c7d44d20 0000000000000000 ffff8801bcb6fa98 [ 28.743527] ffffffff8156c3fe ffff8801c7d44d20 0000000000000008 0000000000000000 [ 28.751521] Call Trace: [ 28.754092] [] dump_stack+0xc1/0x128 [ 28.759466] [] print_address_description+0x6c/0x234 [ 28.766127] [] kasan_report.cold.6+0x242/0x2fe [ 28.772334] [] ? __lock_acquire+0x319b/0x4070 [ 28.778454] [] __asan_report_load8_noabort+0x14/0x20 [ 28.785269] [] __lock_acquire+0x319b/0x4070 [ 28.791220] [] ? dput+0x1f/0x30 [ 28.796125] [] ? __fput+0x42f/0x700 [ 28.801377] [] ? ____fput+0x15/0x20 [ 28.806632] [] ? task_work_run+0x10c/0x180 [ 28.812500] [] ? exit_to_usermode_loop+0xfc/0x120 [ 28.818969] [] ? __lock_acquire+0x654/0x4070 [ 28.825005] [] ? debug_check_no_locks_freed+0x210/0x210 [ 28.831994] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 28.838808] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 28.845623] [] ? check_preemption_disabled+0x3b/0x170 [ 28.852435] [] lock_acquire+0x130/0x3e0 [ 28.858036] [] ? lock_sock_nested+0x43/0x120 [ 28.864073] [] ? sock_release+0x1c0/0x1c0 [ 28.869847] [] _raw_spin_lock_bh+0x3a/0x50 [ 28.875706] [] ? lock_sock_nested+0x43/0x120 [ 28.881735] [] lock_sock_nested+0x43/0x120 [ 28.887600] [] pppol2tp_release+0x50/0x2e0 [ 28.893459] [] sock_release+0x96/0x1c0 [ 28.898972] [] sock_close+0x16/0x20 [ 28.904231] [] __fput+0x263/0x700 [ 28.909310] [] ____fput+0x15/0x20 [ 28.914399] [] task_work_run+0x10c/0x180 [ 28.920085] [] exit_to_usermode_loop+0xfc/0x120 [ 28.926381] [] do_syscall_64+0x364/0x490 [ 28.932063] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.938956] [ 28.940559] Allocated by task 5219: [ 28.944161] save_stack_trace+0x16/0x20 [ 28.948111] save_stack+0x43/0xd0 [ 28.951539] kasan_kmalloc+0xc7/0xe0 [ 28.955236] __kmalloc+0x11d/0x300 [ 28.958748] sk_prot_alloc+0x17e/0x290 [ 28.962607] sk_alloc+0x3a/0x3a0 [ 28.965949] pppol2tp_create+0x33/0x1f0 [ 28.969899] pppox_create+0xf6/0x210 [ 28.973587] __sock_create+0x2ef/0x5f0 [ 28.977446] SyS_socket+0xf0/0x1b0 [ 28.980960] do_syscall_64+0x1a6/0x490 [ 28.984826] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.989898] [ 28.991523] Freed by task 5217: [ 28.994776] save_stack_trace+0x16/0x20 [ 28.998725] save_stack+0x43/0xd0 [ 29.002160] kasan_slab_free+0x72/0xc0 [ 29.006019] kfree+0xfb/0x310 [ 29.009096] __sk_destruct+0x46f/0x590 [ 29.012956] sk_destruct+0x63/0x80 [ 29.016481] __sk_free+0x4f/0x220 [ 29.019935] sk_free+0x2b/0x40 [ 29.023106] pppol2tp_session_sock_put+0x5a/0x70 [ 29.027837] l2tp_tunnel_closeall+0x268/0x350 [ 29.032307] l2tp_udp_encap_destroy+0x87/0xe0 [ 29.036779] udpv6_destroy_sock+0xb1/0xd0 [ 29.040902] sk_common_release+0x6d/0x300 [ 29.045021] udp_lib_close+0x15/0x20 [ 29.048712] inet_release+0xff/0x1d0 [ 29.052401] inet6_release+0x50/0x70 [ 29.056087] sock_release+0x96/0x1c0 [ 29.059775] sock_close+0x16/0x20 [ 29.063202] __fput+0x263/0x700 [ 29.066461] ____fput+0x15/0x20 [ 29.069739] task_work_run+0x10c/0x180 [ 29.073602] exit_to_usermode_loop+0xfc/0x120 [ 29.078084] do_syscall_64+0x364/0x490 [ 29.081945] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 29.087053] [ 29.088665] The buggy address belongs to the object at ffff8801c7d44c80 [ 29.088665] which belongs to the cache kmalloc-2048 of size 2048 [ 29.101474] The buggy address is located 160 bytes inside of [ 29.101474] 2048-byte region [ffff8801c7d44c80, ffff8801c7d45480) [ 29.113421] The buggy address belongs to the page: [ 29.118319] page:ffffea00071f5000 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 29.128551] flags: 0x8000000000004080(slab|head) [ 29.133293] page dumped because: kasan: bad access detected [ 29.138974] [ 29.140589] Memory state around the buggy address: [ 29.145495] ffff8801c7d44c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 29.152826] ffff8801c7d44c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 29.160161] >ffff8801c7d44d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 29.167504] ^ [ 29.171884] ffff8801c7d44d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 29.179222] ffff8801c7d44e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 29.186552] ================================================================== [ 29.193880] Disabling lock debugging due to kernel taint [ 29.199299] Kernel panic - not syncing: panic_on_warn set ... [ 29.199299] [ 29.206637] CPU: 0 PID: 5217 Comm: syz-executor0 Tainted: G B 4.9.123-g8dd3fc2 #79 [ 29.215445] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 29.224773] ffff8801bcb6f9c0 ffffffff81eb9689 ffffffff843c821b 00000000ffffffff [ 29.232766] 0000000000000000 0000000000000000 0000000000000000 ffff8801bcb6fa80 [ 29.240760] ffffffff81423f75 0000000041b58ab3 ffffffff843bb878 ffffffff81423db6 [ 29.248759] Call Trace: [ 29.251516] [] dump_stack+0xc1/0x128 [ 29.256975] [] panic+0x1bf/0x3bc [ 29.261971] [] ? add_taint.cold.6+0x16/0x16 [ 29.267919] [] ? kasan_end_report+0x32/0x4f [ 29.273864] [] kasan_end_report+0x47/0x4f [ 29.279656] [] kasan_report.cold.6+0x76/0x2fe [ 29.285781] [] ? __lock_acquire+0x319b/0x4070 [ 29.291916] [] __asan_report_load8_noabort+0x14/0x20 [ 29.298643] [] __lock_acquire+0x319b/0x4070 [ 29.304607] [] ? dput+0x1f/0x30 [ 29.309510] [] ? __fput+0x42f/0x700 [ 29.314759] [] ? ____fput+0x15/0x20 [ 29.320035] [] ? task_work_run+0x10c/0x180 [ 29.325930] [] ? exit_to_usermode_loop+0xfc/0x120 [ 29.332394] [] ? __lock_acquire+0x654/0x4070 [ 29.338424] [] ? debug_check_no_locks_freed+0x210/0x210 [ 29.345410] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 29.352269] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 29.359102] [] ? check_preemption_disabled+0x3b/0x170 [ 29.366003] [] lock_acquire+0x130/0x3e0 [ 29.371605] [] ? lock_sock_nested+0x43/0x120 [ 29.377652] [] ? sock_release+0x1c0/0x1c0 [ 29.383425] [] _raw_spin_lock_bh+0x3a/0x50 [ 29.389292] [] ? lock_sock_nested+0x43/0x120 [ 29.395326] [] lock_sock_nested+0x43/0x120 [ 29.401205] [] pppol2tp_release+0x50/0x2e0 [ 29.407087] [] sock_release+0x96/0x1c0 [ 29.412604] [] sock_close+0x16/0x20 [ 29.417861] [] __fput+0x263/0x700 [ 29.422941] [] ____fput+0x15/0x20 [ 29.428018] [] task_work_run+0x10c/0x180 [ 29.433703] [] exit_to_usermode_loop+0xfc/0x120 [ 29.439996] [] do_syscall_64+0x364/0x490 [ 29.445681] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 29.452906] Dumping ftrace buffer: [ 29.456424] (ftrace buffer empty) [ 29.460104] Kernel Offset: disabled [ 29.463700] Rebooting in 86400 seconds..