[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.966075] 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: [ 22.170896] random: sshd: uninitialized urandom read (32 bytes read) [ 22.693636] random: sshd: uninitialized urandom read (32 bytes read) [ 23.497116] random: sshd: uninitialized urandom read (32 bytes read) [ 34.469722] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.4' (ECDSA) to the list of known hosts. [ 39.855848] random: sshd: uninitialized urandom read (32 bytes read) 2018/05/19 00:07:55 parsed 1 programs 2018/05/19 00:07:55 executed programs: 0 [ 40.308924] IPVS: Creating netns size=2536 id=1 [ 40.385449] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 40.397555] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 40.438510] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 40.449800] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 40.489878] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 40.500952] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 40.512713] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 40.533305] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 40.968328] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 40.991857] IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready [ 40.998399] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready [ 41.005120] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready 2018/05/19 00:08:00 executed programs: 90 2018/05/19 00:08:05 executed programs: 197 2018/05/19 00:08:10 executed programs: 307 2018/05/19 00:08:15 executed programs: 422 2018/05/19 00:08:20 executed programs: 534 2018/05/19 00:08:25 executed programs: 641 2018/05/19 00:08:30 executed programs: 747 2018/05/19 00:08:35 executed programs: 853 2018/05/19 00:08:40 executed programs: 956 2018/05/19 00:08:45 executed programs: 1062 2018/05/19 00:08:50 executed programs: 1163 2018/05/19 00:08:55 executed programs: 1267 2018/05/19 00:09:00 executed programs: 1375 [ 107.976956] ================================================================== [ 107.984409] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 107.991655] Read of size 4 at addr ffff8801da2e7b80 by task syz-executor0/12760 [ 107.999071] [ 108.000673] CPU: 0 PID: 12760 Comm: syz-executor0 Not tainted 4.9.100-ge14d1a3 #30 [ 108.008347] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 108.017674] ffff8801d42d7868 ffffffff81eb0f09 ffffea000768b980 ffff8801da2e7b80 [ 108.025780] 0000000000000000 ffff8801da2e7b80 ffffffff8300fbe0 ffff8801d42d78a0 [ 108.033790] ffffffff8156532b ffff8801da2e7b80 0000000000000004 0000000000000000 [ 108.041773] Call Trace: [ 108.044341] [] dump_stack+0xc1/0x128 [ 108.049692] [] ? sock_release+0x1c0/0x1c0 [ 108.055475] [] print_address_description+0x6c/0x234 [ 108.062494] [] ? sock_release+0x1c0/0x1c0 [ 108.068263] [] kasan_report.cold.6+0x242/0x2fe [ 108.074466] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 108.081188] [] __asan_report_load4_noabort+0x14/0x20 [ 108.087918] [] l2tp_session_queue_purge+0xf4/0x100 [ 108.094468] [] ? sock_release+0x1c0/0x1c0 [ 108.100237] [] pppol2tp_release+0x1fb/0x2e0 [ 108.106178] [] sock_release+0x96/0x1c0 [ 108.111685] [] sock_close+0x16/0x20 [ 108.116932] [] __fput+0x263/0x700 [ 108.122014] [] ____fput+0x15/0x20 [ 108.127091] [] task_work_run+0x10c/0x180 [ 108.132773] [] do_exit+0x9e1/0x27c0 [ 108.138027] [] ? debug_check_no_locks_freed+0x210/0x210 [ 108.145010] [] ? __lock_acquire+0x654/0x4070 [ 108.151040] [] ? release_task.part.19+0x1210/0x1210 [ 108.157676] [] ? debug_check_no_locks_freed+0x210/0x210 [ 108.164660] [] ? recalc_sigpending+0x72/0x90 [ 108.170690] [] do_group_exit+0x111/0x340 [ 108.176370] [] get_signal+0x4cf/0x1450 [ 108.181880] [] do_signal+0x87/0x19f0 [ 108.187218] [] ? __fd_install+0x24a/0x5d0 [ 108.192986] [] ? get_unused_fd_flags+0xd0/0xd0 [ 108.199192] [] ? get_unused_fd_flags+0xd0/0xd0 [ 108.205398] [] ? setup_sigcontext+0x7d0/0x7d0 [ 108.211517] [] ? fd_install+0x4d/0x60 [ 108.216942] [] ? compat_SyS_get_robust_list+0x310/0x310 [ 108.223927] [] ? SyS_socket+0x121/0x1b0 [ 108.229523] [] ? exit_to_usermode_loop+0xac/0x120 [ 108.235985] [] exit_to_usermode_loop+0xe1/0x120 [ 108.242278] [] do_fast_syscall_32+0x5c3/0x870 [ 108.248416] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 108.255055] [] entry_SYSENTER_compat+0x90/0xa2 [ 108.261263] [ 108.262865] Allocated by task 12756: [ 108.266550] save_stack_trace+0x16/0x20 [ 108.270497] save_stack+0x43/0xd0 [ 108.273921] kasan_kmalloc+0xc7/0xe0 [ 108.277634] __kmalloc+0x11d/0x300 [ 108.281146] l2tp_session_create+0x38/0x16f0 [ 108.285526] pppol2tp_connect+0x10d7/0x18f0 [ 108.289818] SYSC_connect+0x1b8/0x300 [ 108.293588] SyS_connect+0x24/0x30 [ 108.297101] do_fast_syscall_32+0x2f7/0x870 [ 108.301395] entry_SYSENTER_compat+0x90/0xa2 [ 108.305791] [ 108.307391] Freed by task 12747: [ 108.310731] save_stack_trace+0x16/0x20 [ 108.314675] save_stack+0x43/0xd0 [ 108.318100] kasan_slab_free+0x72/0xc0 [ 108.321959] kfree+0xfb/0x310 [ 108.325035] l2tp_session_free+0x166/0x200 [ 108.329241] l2tp_tunnel_closeall+0x284/0x350 [ 108.333707] l2tp_udp_encap_destroy+0x87/0xe0 [ 108.338174] udpv6_destroy_sock+0xb1/0xd0 [ 108.342295] sk_common_release+0x6d/0x300 [ 108.346413] udp_lib_close+0x15/0x20 [ 108.350098] inet_release+0xff/0x1d0 [ 108.353783] inet6_release+0x50/0x70 [ 108.357471] sock_release+0x96/0x1c0 [ 108.361154] sock_close+0x16/0x20 [ 108.364581] __fput+0x263/0x700 [ 108.367841] ____fput+0x15/0x20 [ 108.371096] task_work_run+0x10c/0x180 [ 108.374955] do_exit+0x9e1/0x27c0 [ 108.378380] do_group_exit+0x111/0x340 [ 108.382238] SyS_exit_group+0x1d/0x20 [ 108.386009] do_fast_syscall_32+0x2f7/0x870 [ 108.390303] entry_SYSENTER_compat+0x90/0xa2 [ 108.394679] [ 108.396282] The buggy address belongs to the object at ffff8801da2e7b80 [ 108.396282] which belongs to the cache kmalloc-512 of size 512 [ 108.408909] The buggy address is located 0 bytes inside of [ 108.408909] 512-byte region [ffff8801da2e7b80, ffff8801da2e7d80) [ 108.420577] The buggy address belongs to the page: [ 108.425480] page:ffffea000768b980 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 108.435654] flags: 0x8000000000004080(slab|head) [ 108.440394] page dumped because: kasan: bad access detected [ 108.446072] [ 108.447669] Memory state around the buggy address: [ 108.452570] ffff8801da2e7a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 108.459899] ffff8801da2e7b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 108.467229] >ffff8801da2e7b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 108.474555] ^ [ 108.477892] ffff8801da2e7c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 108.485222] ffff8801da2e7c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 108.492552] ================================================================== [ 108.499881] Disabling lock debugging due to kernel taint [ 108.505549] Kernel panic - not syncing: panic_on_warn set ... [ 108.505549] [ 108.512899] CPU: 0 PID: 12760 Comm: syz-executor0 Tainted: G B 4.9.100-ge14d1a3 #30 [ 108.521797] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 108.531130] ffff8801d42d77c8 ffffffff81eb0f09 ffffffff843c50e5 00000000ffffffff [ 108.539114] 0000000000000000 0000000000000000 ffffffff8300fbe0 ffff8801d42d7888 [ 108.547101] ffffffff8141f895 0000000041b58ab3 ffffffff843b87e8 ffffffff8141f6d6 [ 108.555078] Call Trace: [ 108.557643] [] dump_stack+0xc1/0x128 [ 108.562983] [] ? sock_release+0x1c0/0x1c0 [ 108.568754] [] panic+0x1bf/0x3bc [ 108.573740] [] ? add_taint.cold.6+0x16/0x16 [ 108.579682] [] ? ___preempt_schedule+0x16/0x18 [ 108.585887] [] kasan_end_report+0x47/0x4f [ 108.591656] [] kasan_report.cold.6+0x76/0x2fe [ 108.597772] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 108.604497] [] __asan_report_load4_noabort+0x14/0x20 [ 108.611219] [] l2tp_session_queue_purge+0xf4/0x100 [ 108.617767] [] ? sock_release+0x1c0/0x1c0 [ 108.623533] [] pppol2tp_release+0x1fb/0x2e0 [ 108.629478] [] sock_release+0x96/0x1c0 [ 108.634986] [] sock_close+0x16/0x20 [ 108.640233] [] __fput+0x263/0x700 [ 108.645396] [] ____fput+0x15/0x20 [ 108.650472] [] task_work_run+0x10c/0x180 [ 108.656157] [] do_exit+0x9e1/0x27c0 [ 108.661408] [] ? debug_check_no_locks_freed+0x210/0x210 [ 108.668405] [] ? __lock_acquire+0x654/0x4070 [ 108.674447] [] ? release_task.part.19+0x1210/0x1210 [ 108.681087] [] ? debug_check_no_locks_freed+0x210/0x210 [ 108.688074] [] ? recalc_sigpending+0x72/0x90 [ 108.694106] [] do_group_exit+0x111/0x340 [ 108.699786] [] get_signal+0x4cf/0x1450 [ 108.705298] [] do_signal+0x87/0x19f0 [ 108.710633] [] ? __fd_install+0x24a/0x5d0 [ 108.716400] [] ? get_unused_fd_flags+0xd0/0xd0 [ 108.722602] [] ? get_unused_fd_flags+0xd0/0xd0 [ 108.728807] [] ? setup_sigcontext+0x7d0/0x7d0 [ 108.734923] [] ? fd_install+0x4d/0x60 [ 108.740347] [] ? compat_SyS_get_robust_list+0x310/0x310 [ 108.747333] [] ? SyS_socket+0x121/0x1b0 [ 108.752928] [] ? exit_to_usermode_loop+0xac/0x120 [ 108.759395] [] exit_to_usermode_loop+0xe1/0x120 [ 108.765699] [] do_fast_syscall_32+0x5c3/0x870 [ 108.771818] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 108.778459] [] entry_SYSENTER_compat+0x90/0xa2 [ 108.785097] Dumping ftrace buffer: [ 108.788609] (ftrace buffer empty) [ 108.792294] Kernel Offset: disabled [ 108.795918] Rebooting in 86400 seconds..