[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.851754] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.485429] random: sshd: uninitialized urandom read (32 bytes read) [ 20.712566] random: sshd: uninitialized urandom read (32 bytes read) [ 21.736360] random: sshd: uninitialized urandom read (32 bytes read) [ 21.876576] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.13' (ECDSA) to the list of known hosts. [ 27.406942] random: sshd: uninitialized urandom read (32 bytes read) 2018/06/20 20:01:38 parsed 1 programs [ 28.938330] random: cc1: uninitialized urandom read (8 bytes read) 2018/06/20 20:01:40 executed programs: 0 [ 30.009878] IPVS: Creating netns size=2536 id=1 [ 30.142828] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 30.155553] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 30.202590] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 30.214479] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 30.261633] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 30.273855] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 30.286369] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 30.307900] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 30.943568] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 30.975185] IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready [ 30.981786] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready [ 30.989607] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready 2018/06/20 20:01:45 executed programs: 79 [ 35.718473] ================================================================== [ 35.725870] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 35.733117] Read of size 4 at addr ffff8801cd32ec80 by task syz-executor0/4762 [ 35.740448] [ 35.742057] CPU: 0 PID: 4762 Comm: syz-executor0 Not tainted 4.9.109-ge1815b3 #3 [ 35.749563] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 35.758894] ffff8801cb92f868 ffffffff81eb3e29 ffffea000734cb80 ffff8801cd32ec80 [ 35.766904] 0000000000000000 ffff8801cd32ec80 ffffffff83013be0 ffff8801cb92f8a0 [ 35.774886] ffffffff81567a89 ffff8801cd32ec80 0000000000000004 0000000000000000 [ 35.782913] Call Trace: [ 35.785477] [] dump_stack+0xc1/0x128 [ 35.790820] [] ? sock_release+0x1c0/0x1c0 [ 35.796600] [] print_address_description+0x6c/0x234 [ 35.803239] [] ? sock_release+0x1c0/0x1c0 [ 35.809009] [] kasan_report.cold.6+0x242/0x2fe [ 35.815225] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 35.821952] [] __asan_report_load4_noabort+0x14/0x20 [ 35.828685] [] l2tp_session_queue_purge+0xf4/0x100 [ 35.835237] [] ? sock_release+0x1c0/0x1c0 [ 35.841009] [] pppol2tp_release+0x1fb/0x2e0 [ 35.846951] [] sock_release+0x96/0x1c0 [ 35.852469] [] sock_close+0x16/0x20 [ 35.857720] [] __fput+0x263/0x700 [ 35.862805] [] ____fput+0x15/0x20 [ 35.867890] [] task_work_run+0x10c/0x180 [ 35.873755] [] do_exit+0x9e1/0x27c0 [ 35.879005] [] ? debug_check_no_locks_freed+0x210/0x210 [ 35.886003] [] ? get_futex_key+0x1090/0x1090 [ 35.892050] [] ? __lock_acquire+0x654/0x4070 [ 35.898091] [] ? release_task.part.19+0x1210/0x1210 [ 35.904731] [] ? debug_check_no_locks_freed+0x210/0x210 [ 35.911720] [] ? recalc_sigpending+0x72/0x90 [ 35.917755] [] do_group_exit+0x111/0x340 [ 35.923440] [] get_signal+0x4cf/0x1450 [ 35.928956] [] do_signal+0x87/0x19f0 [ 35.934305] [] ? __fd_install+0x24a/0x5d0 [ 35.940075] [] ? get_unused_fd_flags+0xd0/0xd0 [ 35.946278] [] ? get_unused_fd_flags+0xd0/0xd0 [ 35.952492] [] ? setup_sigcontext+0x7d0/0x7d0 [ 35.958607] [] ? fd_install+0x4d/0x60 [ 35.964036] [] ? compat_SyS_get_robust_list+0x310/0x310 [ 35.971021] [] ? SyS_socket+0x121/0x1b0 [ 35.976635] [] ? exit_to_usermode_loop+0xac/0x120 [ 35.983108] [] exit_to_usermode_loop+0xe1/0x120 [ 35.989484] [] do_fast_syscall_32+0x5c3/0x870 [ 35.995602] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 36.002252] [] entry_SYSENTER_compat+0x90/0xa2 [ 36.008457] [ 36.010070] Allocated by task 4758: [ 36.013686] save_stack_trace+0x16/0x20 [ 36.017633] save_stack+0x43/0xd0 [ 36.021059] kasan_kmalloc+0xc7/0xe0 [ 36.024759] __kmalloc+0x11d/0x300 [ 36.028362] l2tp_session_create+0x38/0x16f0 [ 36.032741] pppol2tp_connect+0x10d7/0x18f0 [ 36.037043] SYSC_connect+0x1b8/0x300 [ 36.040829] SyS_connect+0x24/0x30 [ 36.044355] do_fast_syscall_32+0x2f7/0x870 [ 36.048657] entry_SYSENTER_compat+0x90/0xa2 [ 36.053040] [ 36.054640] Freed by task 4743: [ 36.057893] save_stack_trace+0x16/0x20 [ 36.061849] save_stack+0x43/0xd0 [ 36.065276] kasan_slab_free+0x72/0xc0 [ 36.069136] kfree+0xfb/0x310 [ 36.072213] l2tp_session_free+0x166/0x200 [ 36.076418] l2tp_tunnel_closeall+0x284/0x350 [ 36.080972] l2tp_udp_encap_destroy+0x87/0xe0 [ 36.085448] udpv6_destroy_sock+0xb1/0xd0 [ 36.089566] sk_common_release+0x6d/0x300 [ 36.093683] udp_lib_close+0x15/0x20 [ 36.097369] inet_release+0xff/0x1d0 [ 36.101058] inet6_release+0x50/0x70 [ 36.104745] sock_release+0x96/0x1c0 [ 36.108430] sock_close+0x16/0x20 [ 36.111857] __fput+0x263/0x700 [ 36.115114] ____fput+0x15/0x20 [ 36.118382] task_work_run+0x10c/0x180 [ 36.122242] do_exit+0x9e1/0x27c0 [ 36.125666] do_group_exit+0x111/0x340 [ 36.129525] SyS_exit_group+0x1d/0x20 [ 36.133295] do_fast_syscall_32+0x2f7/0x870 [ 36.137588] entry_SYSENTER_compat+0x90/0xa2 [ 36.141980] [ 36.143580] The buggy address belongs to the object at ffff8801cd32ec80 [ 36.143580] which belongs to the cache kmalloc-512 of size 512 [ 36.156211] The buggy address is located 0 bytes inside of [ 36.156211] 512-byte region [ffff8801cd32ec80, ffff8801cd32ee80) [ 36.167884] The buggy address belongs to the page: [ 36.172789] page:ffffea000734cb80 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 36.183144] flags: 0x8000000000004080(slab|head) [ 36.187872] page dumped because: kasan: bad access detected [ 36.193550] [ 36.195157] Memory state around the buggy address: [ 36.200064] ffff8801cd32eb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 36.207754] ffff8801cd32ec00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 36.215084] >ffff8801cd32ec80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 36.222776] ^ [ 36.226118] ffff8801cd32ed00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 36.233454] ffff8801cd32ed80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 36.240796] ================================================================== [ 36.248128] Disabling lock debugging due to kernel taint [ 36.253857] Kernel panic - not syncing: panic_on_warn set ... [ 36.253857] [ 36.261231] CPU: 0 PID: 4762 Comm: syz-executor0 Tainted: G B 4.9.109-ge1815b3 #3 [ 36.269963] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 36.279484] ffff8801cb92f7c8 ffffffff81eb3e29 ffffffff843c6327 00000000ffffffff [ 36.287493] 0000000000000000 0000000000000000 ffffffff83013be0 ffff8801cb92f888 [ 36.295506] ffffffff81421925 0000000041b58ab3 ffffffff843b9a40 ffffffff81421766 [ 36.303512] Call Trace: [ 36.306087] [] dump_stack+0xc1/0x128 [ 36.311429] [] ? sock_release+0x1c0/0x1c0 [ 36.317204] [] panic+0x1bf/0x3bc [ 36.322382] [] ? add_taint.cold.6+0x16/0x16 [ 36.328328] [] ? ___preempt_schedule+0x16/0x18 [ 36.334535] [] kasan_end_report+0x47/0x4f [ 36.340317] [] kasan_report.cold.6+0x76/0x2fe [ 36.346437] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 36.353163] [] __asan_report_load4_noabort+0x14/0x20 [ 36.359893] [] l2tp_session_queue_purge+0xf4/0x100 [ 36.366536] [] ? sock_release+0x1c0/0x1c0 [ 36.372309] [] pppol2tp_release+0x1fb/0x2e0 [ 36.378253] [] sock_release+0x96/0x1c0 [ 36.383774] [] sock_close+0x16/0x20 [ 36.389112] [] __fput+0x263/0x700 [ 36.394189] [] ____fput+0x15/0x20 [ 36.399444] [] task_work_run+0x10c/0x180 [ 36.405133] [] do_exit+0x9e1/0x27c0 [ 36.410385] [] ? debug_check_no_locks_freed+0x210/0x210 [ 36.417374] [] ? get_futex_key+0x1090/0x1090 [ 36.423409] [] ? __lock_acquire+0x654/0x4070 [ 36.429441] [] ? release_task.part.19+0x1210/0x1210 [ 36.436093] [] ? debug_check_no_locks_freed+0x210/0x210 [ 36.443089] [] ? recalc_sigpending+0x72/0x90 [ 36.449382] [] do_group_exit+0x111/0x340 [ 36.455066] [] get_signal+0x4cf/0x1450 [ 36.460588] [] do_signal+0x87/0x19f0 [ 36.465925] [] ? __fd_install+0x24a/0x5d0 [ 36.471708] [] ? get_unused_fd_flags+0xd0/0xd0 [ 36.477911] [] ? get_unused_fd_flags+0xd0/0xd0 [ 36.484114] [] ? setup_sigcontext+0x7d0/0x7d0 [ 36.490403] [] ? fd_install+0x4d/0x60 [ 36.495840] [] ? compat_SyS_get_robust_list+0x310/0x310 [ 36.502899] [] ? SyS_socket+0x121/0x1b0 [ 36.508610] [] ? exit_to_usermode_loop+0xac/0x120 [ 36.515092] [] exit_to_usermode_loop+0xe1/0x120 [ 36.521403] [] do_fast_syscall_32+0x5c3/0x870 [ 36.527544] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 36.534200] [] entry_SYSENTER_compat+0x90/0xa2 [ 36.540945] Dumping ftrace buffer: [ 36.544547] (ftrace buffer empty) [ 36.548330] Kernel Offset: disabled [ 36.551934] Rebooting in 86400 seconds..