INIT: Entering runlevel: 2 [info] Using makefile-style concurrent boot in runlevel 2. [....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.45' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 25.043094] IPVS: Creating netns size=2536 id=1 [ 25.123384] ================================================================== [ 25.130792] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xe8/0x100 [ 25.138049] Read of size 4 at addr ffff8801b5b90500 by task syzkaller177674/3777 [ 25.145556] [ 25.147161] CPU: 1 PID: 3777 Comm: syzkaller177674 Not tainted 4.9.92-g40a1830 #71 [ 25.154841] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.164175] ffff8801b5947ca8 ffffffff81d95109 ffffea0006d6e400 ffff8801b5b90500 [ 25.172151] 0000000000000000 ffff8801b5b90500 ffffffff82ed79f0 ffff8801b5947ce0 [ 25.180124] ffffffff8153d5d3 ffff8801b5b90500 0000000000000004 0000000000000000 [ 25.188121] Call Trace: [ 25.190687] [] dump_stack+0xc1/0x128 [ 25.196035] [] ? sock_release+0x1e0/0x1e0 [ 25.201816] [] print_address_description+0x73/0x280 [ 25.208469] [] ? sock_release+0x1e0/0x1e0 [ 25.214244] [] kasan_report+0x255/0x380 [ 25.219851] [] ? l2tp_session_queue_purge+0xe8/0x100 [ 25.226578] [] __asan_report_load4_noabort+0x14/0x20 [ 25.233324] [] l2tp_session_queue_purge+0xe8/0x100 [ 25.239883] [] ? sock_release+0x1e0/0x1e0 [ 25.245658] [] pppol2tp_release+0x1ff/0x2e0 [ 25.251601] [] sock_release+0x8d/0x1e0 [ 25.257115] [] sock_close+0x16/0x20 [ 25.262371] [] __fput+0x28c/0x6e0 [ 25.267469] [] ____fput+0x15/0x20 [ 25.272549] [] task_work_run+0x115/0x190 [ 25.278246] [] exit_to_usermode_loop+0xfc/0x120 [ 25.284547] [] do_syscall_64+0x36f/0x490 [ 25.290249] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.297157] [ 25.298777] Allocated by task 3774: [ 25.302379] save_stack_trace+0x16/0x20 [ 25.306325] save_stack+0x43/0xd0 [ 25.309749] kasan_kmalloc+0xad/0xe0 [ 25.313431] __kmalloc+0x11d/0x310 [ 25.316945] l2tp_session_create+0x38/0x1770 [ 25.321325] pppol2tp_connect+0x10fe/0x18f0 [ 25.325633] SYSC_connect+0x1b6/0x310 [ 25.329401] SyS_connect+0x24/0x30 [ 25.332927] do_syscall_64+0x1a4/0x490 [ 25.336787] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.341860] [ 25.343473] Freed by task 3774: [ 25.346730] save_stack_trace+0x16/0x20 [ 25.350677] save_stack+0x43/0xd0 [ 25.354100] kasan_slab_free+0x72/0xc0 [ 25.357956] kfree+0x103/0x300 [ 25.361128] l2tp_session_free+0x166/0x200 [ 25.365331] l2tp_tunnel_closeall+0x26c/0x3a0 [ 25.369796] l2tp_udp_encap_destroy+0x87/0xe0 [ 25.374268] udpv6_destroy_sock+0xb1/0xd0 [ 25.378393] sk_common_release+0x6b/0x2f0 [ 25.382512] udp_lib_close+0x15/0x20 [ 25.386205] inet_release+0xfa/0x1d0 [ 25.389891] inet6_release+0x50/0x70 [ 25.393597] sock_release+0x8d/0x1e0 [ 25.397288] sock_close+0x16/0x20 [ 25.400709] __fput+0x28c/0x6e0 [ 25.403957] ____fput+0x15/0x20 [ 25.407220] task_work_run+0x115/0x190 [ 25.411086] exit_to_usermode_loop+0xfc/0x120 [ 25.415549] do_syscall_64+0x36f/0x490 [ 25.419411] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.424489] [ 25.426098] The buggy address belongs to the object at ffff8801b5b90500 [ 25.426098] which belongs to the cache kmalloc-512 of size 512 [ 25.438724] The buggy address is located 0 bytes inside of [ 25.438724] 512-byte region [ffff8801b5b90500, ffff8801b5b90700) [ 25.450394] The buggy address belongs to the page: [ 25.455318] page:ffffea0006d6e400 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 25.465503] flags: 0x8000000000004080(slab|head) [ 25.470225] page dumped because: kasan: bad access detected [ 25.475901] [ 25.477498] Memory state around the buggy address: [ 25.482396] ffff8801b5b90400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 25.489732] ffff8801b5b90480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 25.497058] >ffff8801b5b90500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 25.504383] ^ [ 25.507717] ffff8801b5b90580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 25.515046] ffff8801b5b90600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 25.522380] ================================================================== [ 25.529707] Disabling lock debugging due to kernel taint [ 25.535478] Kernel panic - not syncing: panic_on_warn set ... [ 25.535478] [ 25.542830] CPU: 1 PID: 3777 Comm: syzkaller177674 Tainted: G B 4.9.92-g40a1830 #71 [ 25.551724] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.561055] ffff8801b5947c00 ffffffff81d95109 ffffffff84197d5f ffff8801b5947cd8 [ 25.569041] 0000000000000000 ffff8801b5b90500 ffffffff82ed79f0 ffff8801b5947cc8 [ 25.577009] ffffffff8142e791 0000000041b58ab3 ffffffff8418b7b8 ffffffff8142e5d5 [ 25.584986] Call Trace: [ 25.587550] [] dump_stack+0xc1/0x128 [ 25.592888] [] ? sock_release+0x1e0/0x1e0 [ 25.598658] [] panic+0x1bc/0x3a8 [ 25.603645] [] ? percpu_up_read_preempt_enable.constprop.53+0xd7/0xd7 [ 25.611848] [] ? preempt_schedule+0x25/0x30 [ 25.617789] [] ? ___preempt_schedule+0x16/0x18 [ 25.624003] [] kasan_end_report+0x50/0x50 [ 25.629783] [] kasan_report+0x16b/0x380 [ 25.635392] [] ? l2tp_session_queue_purge+0xe8/0x100 [ 25.642128] [] __asan_report_load4_noabort+0x14/0x20 [ 25.648866] [] l2tp_session_queue_purge+0xe8/0x100 [ 25.655432] [] ? sock_release+0x1e0/0x1e0 [ 25.661217] [] pppol2tp_release+0x1ff/0x2e0 [ 25.667171] [] sock_release+0x8d/0x1e0 [ 25.672676] [] sock_close+0x16/0x20 [ 25.677923] [] __fput+0x28c/0x6e0 [ 25.682996] [] ____fput+0x15/0x20 [ 25.688071] [] task_work_run+0x115/0x190 [ 25.693757] [] exit_to_usermode_loop+0xfc/0x120 [ 25.700055] [] do_syscall_64+0x36f/0x490 [ 25.705744] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.713122] Dumping ftrace buffer: [ 25.716638] (ftrace buffer empty) [ 25.720322] Kernel Offset: disabled [ 25.723921] Rebooting in 86400 seconds..