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 '10.128.0.35' (ECDSA) to the list of known hosts. 2018/04/16 08:23:06 parsed 1 programs 2018/04/16 08:23:06 executed programs: 0 syzkaller login: [ 20.022578] IPVS: Creating netns size=2536 id=1 [ 20.054831] IPVS: Creating netns size=2536 id=2 [ 20.089953] IPVS: Creating netns size=2536 id=3 [ 20.122359] IPVS: Creating netns size=2536 id=4 [ 20.154895] IPVS: Creating netns size=2536 id=5 [ 20.168667] IPVS: Creating netns size=2536 id=6 [ 20.199629] IPVS: Creating netns size=2536 id=7 [ 20.224842] IPVS: Creating netns size=2536 id=8 [ 24.381720] ================================================================== [ 24.389121] BUG: KASAN: use-after-free in pppol2tp_session_destruct+0xed/0x110 [ 24.396463] Read of size 4 at addr ffff8801da3d6500 by task syz-executor5/3983 [ 24.403792] [ 24.405404] CPU: 0 PID: 3983 Comm: syz-executor5 Not tainted 4.9.94-g8683408 #3 [ 24.412824] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.422149] ffff8801d833fc20 ffffffff81d9b509 ffffea000768f580 ffff8801da3d6500 [ 24.430150] 0000000000000000 ffff8801da3d6500 ffffffff82eecbe0 ffff8801d833fc58 [ 24.438182] ffffffff815652cb ffff8801da3d6500 0000000000000004 0000000000000000 [ 24.446212] Call Trace: [ 24.448788] [] dump_stack+0xc1/0x128 [ 24.454142] [] ? sock_release+0x1c0/0x1c0 [ 24.459917] [] print_address_description+0x6c/0x234 [ 24.466559] [] ? sock_release+0x1c0/0x1c0 [ 24.472332] [] kasan_report.cold.6+0x242/0x2fe [ 24.478549] [] ? pppol2tp_session_destruct+0xed/0x110 [ 24.485369] [] __asan_report_load4_noabort+0x14/0x20 [ 24.492108] [] pppol2tp_session_destruct+0xed/0x110 [ 24.498755] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.505047] [] __sk_destruct+0x55/0x590 [ 24.510647] [] ? sock_release+0x1c0/0x1c0 [ 24.516426] [] sk_destruct+0x63/0x80 [ 24.521777] [] __sk_free+0x15e/0x220 [ 24.527122] [] sk_free+0x2b/0x40 [ 24.532115] [] pppol2tp_release+0x239/0x2e0 [ 24.538066] [] sock_release+0x96/0x1c0 [ 24.543574] [] sock_close+0x16/0x20 [ 24.548822] [] __fput+0x263/0x700 [ 24.553899] [] ____fput+0x15/0x20 [ 24.558976] [] task_work_run+0x10c/0x180 [ 24.564660] [] exit_to_usermode_loop+0xfc/0x120 [ 24.570948] [] do_fast_syscall_32+0x5c3/0x870 [ 24.577065] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 24.583703] [] entry_SYSENTER_compat+0x90/0xa2 [ 24.589908] [ 24.591508] Allocated by task 3983: [ 24.595114] save_stack_trace+0x16/0x20 [ 24.599060] save_stack+0x43/0xd0 [ 24.602483] kasan_kmalloc+0xc7/0xe0 [ 24.606181] __kmalloc+0x11d/0x300 [ 24.609692] l2tp_session_create+0x38/0x16f0 [ 24.614072] pppol2tp_connect+0x10c5/0x18e0 [ 24.618371] SYSC_connect+0x1b8/0x300 [ 24.622144] SyS_connect+0x24/0x30 [ 24.625657] do_fast_syscall_32+0x2f7/0x870 [ 24.629957] entry_SYSENTER_compat+0x90/0xa2 [ 24.634340] [ 24.635946] Freed by task 4014: [ 24.639199] save_stack_trace+0x16/0x20 [ 24.643148] save_stack+0x43/0xd0 [ 24.646579] kasan_slab_free+0x72/0xc0 [ 24.650442] kfree+0xfb/0x310 [ 24.653537] l2tp_session_free+0x166/0x200 [ 24.657745] l2tp_tunnel_closeall+0x284/0x350 [ 24.662218] l2tp_udp_encap_destroy+0x87/0xe0 [ 24.666687] udpv6_destroy_sock+0xb1/0xd0 [ 24.670808] sk_common_release+0x6d/0x300 [ 24.674925] udp_lib_close+0x15/0x20 [ 24.678624] inet_release+0xff/0x1d0 [ 24.682323] inet6_release+0x50/0x70 [ 24.686008] sock_release+0x96/0x1c0 [ 24.689693] sock_close+0x16/0x20 [ 24.693121] __fput+0x263/0x700 [ 24.696371] ____fput+0x15/0x20 [ 24.699625] task_work_run+0x10c/0x180 [ 24.703486] exit_to_usermode_loop+0xfc/0x120 [ 24.707959] do_fast_syscall_32+0x5c3/0x870 [ 24.712254] entry_SYSENTER_compat+0x90/0xa2 [ 24.716645] [ 24.718249] The buggy address belongs to the object at ffff8801da3d6500 [ 24.718249] which belongs to the cache kmalloc-512 of size 512 [ 24.730877] The buggy address is located 0 bytes inside of [ 24.730877] 512-byte region [ffff8801da3d6500, ffff8801da3d6700) [ 24.742552] The buggy address belongs to the page: [ 24.747451] page:ffffea000768f580 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 24.757632] flags: 0x8000000000004080(slab|head) [ 24.762355] page dumped because: kasan: bad access detected [ 24.768033] [ 24.769644] Memory state around the buggy address: [ 24.774551] ffff8801da3d6400: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc [ 24.781885] ffff8801da3d6480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 24.789215] >ffff8801da3d6500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 24.796543] ^ [ 24.799881] ffff8801da3d6580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 24.807210] ffff8801da3d6600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 24.814542] ================================================================== [ 24.821876] Disabling lock debugging due to kernel taint [ 24.832886] Kernel panic - not syncing: panic_on_warn set ... [ 24.832886] [ 24.840261] CPU: 0 PID: 3983 Comm: syz-executor5 Tainted: G B 4.9.94-g8683408 #3 [ 24.848907] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.858235] ffff8801d833fb80 ffffffff81d9b509 ffffffff841a8a65 00000000ffffffff [ 24.866232] 0000000000000000 0000000000000000 ffffffff82eecbe0 ffff8801d833fc40 [ 24.874255] ffffffff8141f845 0000000041b58ab3 ffffffff8419c168 ffffffff8141f686 [ 24.882253] Call Trace: [ 24.884815] [] dump_stack+0xc1/0x128 [ 24.890151] [] ? sock_release+0x1c0/0x1c0 [ 24.895923] [] panic+0x1bf/0x3bc [ 24.900919] [] ? add_taint.cold.6+0x16/0x16 [ 24.906875] [] ? ___preempt_schedule+0x16/0x18 [ 24.913082] [] kasan_end_report+0x47/0x4f [ 24.918856] [] kasan_report.cold.6+0x76/0x2fe [ 24.924981] [] ? pppol2tp_session_destruct+0xed/0x110 [ 24.931796] [] __asan_report_load4_noabort+0x14/0x20 [ 24.938528] [] pppol2tp_session_destruct+0xed/0x110 [ 24.945164] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.951461] [] __sk_destruct+0x55/0x590 [ 24.957055] [] ? sock_release+0x1c0/0x1c0 [ 24.962823] [] sk_destruct+0x63/0x80 [ 24.968164] [] __sk_free+0x15e/0x220 [ 24.973504] [] sk_free+0x2b/0x40 [ 24.978489] [] pppol2tp_release+0x239/0x2e0 [ 24.984434] [] sock_release+0x96/0x1c0 [ 24.989953] [] sock_close+0x16/0x20 [ 24.995205] [] __fput+0x263/0x700 [ 25.000280] [] ____fput+0x15/0x20 [ 25.005357] [] task_work_run+0x10c/0x180 [ 25.011039] [] exit_to_usermode_loop+0xfc/0x120 [ 25.017328] [] do_fast_syscall_32+0x5c3/0x870 [ 25.023445] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 25.030088] [] entry_SYSENTER_compat+0x90/0xa2 [ 25.036767] Dumping ftrace buffer: [ 25.040281] (ftrace buffer empty) [ 25.043961] Kernel Offset: disabled [ 25.047564] Rebooting in 86400 seconds..