INIT: Entering runlevel: 2 [[36minfo[39;49m] Using makefile-style concurrent boot in runlevel 2. [....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.48' (ECDSA) to the list of known hosts. 2018/04/03 14:46:46 parsed 1 programs 2018/04/03 14:46:46 executed programs: 0 syzkaller login: [ 47.089640] IPVS: Creating netns size=2536 id=1 [ 47.313475] ================================================================== [ 47.320857] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xe8/0x100 [ 47.328096] Read of size 4 at addr ffff8801c6c1c280 by task syz-executor0/3808 [ 47.335418] [ 47.337016] CPU: 0 PID: 3808 Comm: syz-executor0 Not tainted 4.9.92-g40a1830 #11 [ 47.344515] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 47.353837] ffff8801d8947a20 ffffffff81d95109 ffffea00071b0700 ffff8801c6c1c280 [ 47.361798] 0000000000000000 ffff8801c6c1c280 ffffffff82ed79f0 ffff8801d8947a58 [ 47.369760] ffffffff8153d5d3 ffff8801c6c1c280 0000000000000004 0000000000000000 [ 47.377724] Call Trace: [ 47.380281] [] dump_stack+0xc1/0x128 [ 47.385618] [] ? sock_release+0x1e0/0x1e0 [ 47.391391] [] print_address_description+0x73/0x280 [ 47.398024] [] ? sock_release+0x1e0/0x1e0 [ 47.403786] [] kasan_report+0x255/0x380 [ 47.409377] [] ? l2tp_session_queue_purge+0xe8/0x100 [ 47.416097] [] __asan_report_load4_noabort+0x14/0x20 [ 47.423168] [] l2tp_session_queue_purge+0xe8/0x100 [ 47.429718] [] ? sock_release+0x1e0/0x1e0 [ 47.435483] [] pppol2tp_release+0x1ff/0x2e0 [ 47.441427] [] sock_release+0x8d/0x1e0 [ 47.446930] [] sock_close+0x16/0x20 [ 47.452172] [] __fput+0x28c/0x6e0 [ 47.457240] [] ____fput+0x15/0x20 [ 47.462310] [] task_work_run+0x115/0x190 [ 47.467992] [] get_signal+0x11b0/0x14e0 [ 47.473585] [] ? exit_robust_list+0x230/0x230 [ 47.479699] [] ? __lock_is_held+0xa1/0xf0 [ 47.485472] [] ? locks_remove_posix+0x258/0x510 [ 47.491761] [] do_signal+0x87/0x19f0 [ 47.497098] [] ? __fd_install+0x25e/0x5f0 [ 47.502868] [] ? get_unused_fd_flags+0xd0/0xd0 [ 47.509069] [] ? get_unused_fd_flags+0xd0/0xd0 [ 47.515269] [] ? setup_sigcontext+0x7d0/0x7d0 [ 47.521386] [] ? check_preemption_disabled+0x3b/0x200 [ 47.528202] [] ? kick_process+0x110/0x170 [ 47.533968] [] ? task_work_add+0x8a/0xe0 [ 47.539647] [] ? fput+0xd2/0x140 [ 47.544631] [] ? filp_close+0x103/0x150 [ 47.550223] [] ? exit_to_usermode_loop+0xac/0x120 [ 47.556681] [] exit_to_usermode_loop+0xe1/0x120 [ 47.562968] [] do_fast_syscall_32+0x5c1/0x870 [ 47.569078] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 47.575712] [] entry_SYSENTER_compat+0x90/0xa2 [ 47.581910] [ 47.583509] Allocated by task 3803: [ 47.587103] save_stack_trace+0x16/0x20 [ 47.591048] save_stack+0x43/0xd0 [ 47.594468] kasan_kmalloc+0xad/0xe0 [ 47.598152] __kmalloc+0x11d/0x310 [ 47.601664] l2tp_session_create+0x38/0x1770 [ 47.606038] pppol2tp_connect+0x10fe/0x18f0 [ 47.610328] SYSC_connect+0x1b6/0x310 [ 47.614094] SyS_connect+0x24/0x30 [ 47.617600] do_fast_syscall_32+0x2f5/0x870 [ 47.621888] entry_SYSENTER_compat+0x90/0xa2 [ 47.626261] [ 47.627860] Freed by task 3803: [ 47.631107] save_stack_trace+0x16/0x20 [ 47.635055] save_stack+0x43/0xd0 [ 47.638474] kasan_slab_free+0x72/0xc0 [ 47.642328] kfree+0x103/0x300 [ 47.645491] l2tp_session_free+0x166/0x200 [ 47.649691] l2tp_tunnel_closeall+0x26c/0x3a0 [ 47.654152] l2tp_udp_encap_destroy+0x87/0xe0 [ 47.658615] udpv6_destroy_sock+0xb1/0xd0 [ 47.662731] sk_common_release+0x6b/0x2f0 [ 47.666843] udp_lib_close+0x15/0x20 [ 47.670523] inet_release+0xfa/0x1d0 [ 47.674206] inet6_release+0x50/0x70 [ 47.677887] sock_release+0x8d/0x1e0 [ 47.681567] sock_close+0x16/0x20 [ 47.684988] __fput+0x28c/0x6e0 [ 47.688265] ____fput+0x15/0x20 [ 47.691513] task_work_run+0x115/0x190 [ 47.695368] exit_to_usermode_loop+0xfc/0x120 [ 47.699827] do_fast_syscall_32+0x5c1/0x870 [ 47.704113] entry_SYSENTER_compat+0x90/0xa2 [ 47.708485] [ 47.710080] The buggy address belongs to the object at ffff8801c6c1c280 [ 47.710080] which belongs to the cache kmalloc-512 of size 512 [ 47.722705] The buggy address is located 0 bytes inside of [ 47.722705] 512-byte region [ffff8801c6c1c280, ffff8801c6c1c480) [ 47.734371] The buggy address belongs to the page: [ 47.739266] page:ffffea00071b0700 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 47.749429] flags: 0x8000000000004080(slab|head) [ 47.754149] page dumped because: kasan: bad access detected [ 47.759822] [ 47.761418] Memory state around the buggy address: [ 47.766325] ffff8801c6c1c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.773650] ffff8801c6c1c200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 47.780975] >ffff8801c6c1c280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.788305] ^ [ 47.791638] ffff8801c6c1c300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.798962] ffff8801c6c1c380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.806287] ================================================================== [ 47.813610] Disabling lock debugging due to kernel taint [ 47.819160] Kernel panic - not syncing: panic_on_warn set ... [ 47.819160] [ 47.826498] CPU: 0 PID: 3808 Comm: syz-executor0 Tainted: G B 4.9.92-g40a1830 #11 [ 47.835214] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 47.844538] ffff8801d8947978 ffffffff81d95109 ffffffff84197d5f ffff8801d8947a50 [ 47.853377] 0000000000000000 ffff8801c6c1c280 ffffffff82ed79f0 ffff8801d8947a40 [ 47.861336] ffffffff8142e791 0000000041b58ab3 ffffffff8418b7b8 ffffffff8142e5d5 [ 47.869303] Call Trace: [ 47.871859] [] dump_stack+0xc1/0x128 [ 47.877196] [] ? sock_release+0x1e0/0x1e0 [ 47.882961] [] panic+0x1bc/0x3a8 [ 47.887946] [] ? percpu_up_read_preempt_enable.constprop.53+0xd7/0xd7 [ 47.896144] [] ? preempt_schedule+0x25/0x30 [ 47.902081] [] ? ___preempt_schedule+0x16/0x18 [ 47.908282] [] kasan_end_report+0x50/0x50 [ 47.914049] [] kasan_report+0x16b/0x380 [ 47.919653] [] ? l2tp_session_queue_purge+0xe8/0x100 [ 47.926371] [] __asan_report_load4_noabort+0x14/0x20 [ 47.933089] [] l2tp_session_queue_purge+0xe8/0x100 [ 47.939652] [] ? sock_release+0x1e0/0x1e0 [ 47.945431] [] pppol2tp_release+0x1ff/0x2e0 [ 47.951391] [] sock_release+0x8d/0x1e0 [ 47.956899] [] sock_close+0x16/0x20 [ 47.962143] [] __fput+0x28c/0x6e0 [ 47.967216] [] ____fput+0x15/0x20 [ 47.972288] [] task_work_run+0x115/0x190 [ 47.977966] [] get_signal+0x11b0/0x14e0 [ 47.983557] [] ? exit_robust_list+0x230/0x230 [ 47.989673] [] ? __lock_is_held+0xa1/0xf0 [ 47.995453] [] ? locks_remove_posix+0x258/0x510 [ 48.001739] [] do_signal+0x87/0x19f0 [ 48.007067] [] ? __fd_install+0x25e/0x5f0 [ 48.012830] [] ? get_unused_fd_flags+0xd0/0xd0 [ 48.019030] [] ? get_unused_fd_flags+0xd0/0xd0 [ 48.025228] [] ? setup_sigcontext+0x7d0/0x7d0 [ 48.031341] [] ? check_preemption_disabled+0x3b/0x200 [ 48.038147] [] ? kick_process+0x110/0x170 [ 48.043912] [] ? task_work_add+0x8a/0xe0 [ 48.049587] [] ? fput+0xd2/0x140 [ 48.054568] [] ? filp_close+0x103/0x150 [ 48.060160] [] ? exit_to_usermode_loop+0xac/0x120 [ 48.066617] [] exit_to_usermode_loop+0xe1/0x120 [ 48.072905] [] do_fast_syscall_32+0x5c1/0x870 [ 48.079014] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 48.085648] [] entry_SYSENTER_compat+0x90/0xa2 [ 48.092222] Dumping ftrace buffer: [ 48.095732] (ftrace buffer empty) [ 48.099409] Kernel Offset: disabled [ 48.103003] Rebooting in 86400 seconds..