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 '10.128.0.18' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 24.760087] ================================================================== [ 24.767484] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xe8/0x100 [ 24.774729] Read of size 4 at addr ffff8801cc104000 by task syzkaller701447/3773 [ 24.782228] [ 24.783826] CPU: 0 PID: 3773 Comm: syzkaller701447 Not tainted 4.9.92-g9c3fb9c #70 [ 24.791519] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.800845] ffff8801bd40fca8 ffffffff81d95109 ffffea0007304100 ffff8801cc104000 [ 24.808812] 0000000000000000 ffff8801cc104000 ffffffff82ed79f0 ffff8801bd40fce0 [ 24.816779] ffffffff8153d5d3 ffff8801cc104000 0000000000000004 0000000000000000 [ 24.824745] Call Trace: [ 24.827305] [] dump_stack+0xc1/0x128 [ 24.832639] [] ? sock_release+0x1e0/0x1e0 [ 24.838407] [] print_address_description+0x73/0x280 [ 24.845040] [] ? sock_release+0x1e0/0x1e0 [ 24.850803] [] kasan_report+0x255/0x380 [ 24.856396] [] ? l2tp_session_queue_purge+0xe8/0x100 [ 24.863117] [] __asan_report_load4_noabort+0x14/0x20 [ 24.869849] [] l2tp_session_queue_purge+0xe8/0x100 [ 24.876397] [] ? sock_release+0x1e0/0x1e0 [ 24.882165] [] pppol2tp_release+0x1ff/0x2e0 [ 24.888106] [] sock_release+0x8d/0x1e0 [ 24.893610] [] sock_close+0x16/0x20 [ 24.898857] [] __fput+0x28c/0x6e0 [ 24.903933] [] ____fput+0x15/0x20 [ 24.909008] [] task_work_run+0x115/0x190 [ 24.914693] [] exit_to_usermode_loop+0xfc/0x120 [ 24.920980] [] do_syscall_64+0x36f/0x490 [ 24.926660] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.933550] [ 24.935148] Allocated by task 3772: [ 24.938745] save_stack_trace+0x16/0x20 [ 24.942697] save_stack+0x43/0xd0 [ 24.946119] kasan_kmalloc+0xad/0xe0 [ 24.949798] __kmalloc+0x11d/0x310 [ 24.953309] l2tp_session_create+0x38/0x1770 [ 24.957690] pppol2tp_connect+0x10fe/0x18f0 [ 24.961982] SYSC_connect+0x1b6/0x310 [ 24.965748] SyS_connect+0x24/0x30 [ 24.969258] do_syscall_64+0x1a4/0x490 [ 24.973114] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.978180] [ 24.979778] Freed by task 3772: [ 24.983034] save_stack_trace+0x16/0x20 [ 24.986976] save_stack+0x43/0xd0 [ 24.990402] kasan_slab_free+0x72/0xc0 [ 24.994255] kfree+0x103/0x300 [ 24.997417] l2tp_session_free+0x166/0x200 [ 25.001619] l2tp_tunnel_closeall+0x26c/0x3a0 [ 25.006083] l2tp_udp_encap_destroy+0x87/0xe0 [ 25.010548] udpv6_destroy_sock+0xb1/0xd0 [ 25.014665] sk_common_release+0x6b/0x2f0 [ 25.018789] udp_lib_close+0x15/0x20 [ 25.022471] inet_release+0xfa/0x1d0 [ 25.026156] inet6_release+0x50/0x70 [ 25.029851] sock_release+0x8d/0x1e0 [ 25.033537] sock_close+0x16/0x20 [ 25.036957] __fput+0x28c/0x6e0 [ 25.040203] ____fput+0x15/0x20 [ 25.043453] task_work_run+0x115/0x190 [ 25.047310] exit_to_usermode_loop+0xfc/0x120 [ 25.051773] do_syscall_64+0x36f/0x490 [ 25.055630] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.060707] [ 25.062302] The buggy address belongs to the object at ffff8801cc104000 [ 25.062302] which belongs to the cache kmalloc-512 of size 512 [ 25.074934] The buggy address is located 0 bytes inside of [ 25.074934] 512-byte region [ffff8801cc104000, ffff8801cc104200) [ 25.086601] The buggy address belongs to the page: [ 25.091498] page:ffffea0007304100 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 25.101671] flags: 0x8000000000004080(slab|head) [ 25.106390] page dumped because: kasan: bad access detected [ 25.112065] [ 25.113660] Memory state around the buggy address: [ 25.118560] ffff8801cc103f00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc [ 25.125886] ffff8801cc103f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 25.133210] >ffff8801cc104000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 25.140533] ^ [ 25.143865] ffff8801cc104080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 25.151189] ffff8801cc104100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 25.158514] ================================================================== [ 25.165839] Disabling lock debugging due to kernel taint [ 25.171342] Kernel panic - not syncing: panic_on_warn set ... [ 25.171342] [ 25.178697] CPU: 0 PID: 3773 Comm: syzkaller701447 Tainted: G B 4.9.92-g9c3fb9c #70 [ 25.187587] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.196910] ffff8801bd40fc00 ffffffff81d95109 ffffffff84197d5f ffff8801bd40fcd8 [ 25.204880] 0000000000000000 ffff8801cc104000 ffffffff82ed79f0 ffff8801bd40fcc8 [ 25.212847] ffffffff8142e791 0000000041b58ab3 ffffffff8418b7b8 ffffffff8142e5d5 [ 25.220810] Call Trace: [ 25.223370] [] dump_stack+0xc1/0x128 [ 25.228715] [] ? sock_release+0x1e0/0x1e0 [ 25.234483] [] panic+0x1bc/0x3a8 [ 25.239467] [] ? percpu_up_read_preempt_enable.constprop.53+0xd7/0xd7 [ 25.247668] [] ? preempt_schedule+0x25/0x30 [ 25.253607] [] ? ___preempt_schedule+0x16/0x18 [ 25.259809] [] kasan_end_report+0x50/0x50 [ 25.265574] [] kasan_report+0x16b/0x380 [ 25.271167] [] ? l2tp_session_queue_purge+0xe8/0x100 [ 25.277888] [] __asan_report_load4_noabort+0x14/0x20 [ 25.284609] [] l2tp_session_queue_purge+0xe8/0x100 [ 25.291156] [] ? sock_release+0x1e0/0x1e0 [ 25.296924] [] pppol2tp_release+0x1ff/0x2e0 [ 25.302865] [] sock_release+0x8d/0x1e0 [ 25.308370] [] sock_close+0x16/0x20 [ 25.313618] [] __fput+0x28c/0x6e0 [ 25.318687] [] ____fput+0x15/0x20 [ 25.323762] [] task_work_run+0x115/0x190 [ 25.329440] [] exit_to_usermode_loop+0xfc/0x120 [ 25.335725] [] do_syscall_64+0x36f/0x490 [ 25.341403] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.348773] Dumping ftrace buffer: [ 25.352286] (ftrace buffer empty) [ 25.355964] Kernel Offset: disabled [ 25.359562] Rebooting in 86400 seconds..