[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.970773] 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: [ 21.954256] random: sshd: uninitialized urandom read (32 bytes read) [ 22.444282] random: sshd: uninitialized urandom read (32 bytes read) [ 23.283932] random: sshd: uninitialized urandom read (32 bytes read) [ 23.434788] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.22' (ECDSA) to the list of known hosts. [ 28.910642] random: sshd: uninitialized urandom read (32 bytes read) 2018/05/12 01:54:10 parsed 1 programs 2018/05/12 01:54:10 executed programs: 0 [ 29.445573] IPVS: Creating netns size=2536 id=1 [ 29.482884] IPVS: Creating netns size=2536 id=2 [ 29.506081] IPVS: Creating netns size=2536 id=3 [ 29.541645] IPVS: Creating netns size=2536 id=4 [ 29.565328] IPVS: Creating netns size=2536 id=5 [ 29.581865] IPVS: Creating netns size=2536 id=6 [ 29.624916] IPVS: Creating netns size=2536 id=7 [ 29.651145] IPVS: Creating netns size=2536 id=8 [ 29.717341] l2tp_core: tunl 4: sockfd_lookup(fd=9) returned -9 [ 29.806349] l2tp_core: tunl 4: sockfd_lookup(fd=9) returned -9 [ 29.843511] l2tp_core: tunl 4: sockfd_lookup(fd=10) returned -9 [ 29.853771] l2tp_core: tunl 4: sockfd_lookup(fd=10) returned -9 [ 30.126961] l2tp_core: tunl 4: sockfd_lookup(fd=10) returned -9 [ 30.133366] l2tp_core: tunl 4: sockfd_lookup(fd=9) returned -9 [ 30.222840] l2tp_core: tunl 4: sockfd_lookup(fd=9) returned -9 [ 30.442421] l2tp_core: tunl 4: sockfd_lookup(fd=9) returned -9 [ 30.496097] l2tp_core: tunl 4: sockfd_lookup(fd=9) returned -9 [ 30.503730] l2tp_core: tunl 4: sockfd_lookup(fd=10) returned -9 [ 30.568592] l2tp_core: tunl 4: sockfd_lookup(fd=9) returned -9 [ 30.619125] l2tp_core: tunl 4: sockfd_lookup(fd=9) returned -9 [ 30.673334] l2tp_core: tunl 4: sockfd_lookup(fd=9) returned -9 [ 30.741149] ================================================================== [ 30.748653] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 30.755975] Read of size 4 at addr ffff8801da1d5180 by task syz-executor6/4072 [ 30.763324] [ 30.764945] CPU: 0 PID: 4072 Comm: syz-executor6 Not tainted 4.9.99-gc2f9bce #25 [ 30.772465] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.781807] ffff8801d7d3fa28 ffffffff81eb0f09 ffffea0007687500 ffff8801da1d5180 [ 30.789954] 0000000000000000 ffff8801da1d5180 ffffffff8300fbe0 ffff8801d7d3fa60 [ 30.797998] ffffffff815652eb ffff8801da1d5180 0000000000000004 0000000000000000 [ 30.806055] Call Trace: [ 30.808672] [] dump_stack+0xc1/0x128 [ 30.814064] [] ? sock_release+0x1c0/0x1c0 [ 30.819864] [] print_address_description+0x6c/0x234 [ 30.826528] [] ? sock_release+0x1c0/0x1c0 [ 30.832314] [] kasan_report.cold.6+0x242/0x2fe [ 30.838543] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 30.845294] [] __asan_report_load4_noabort+0x14/0x20 [ 30.852041] [] l2tp_session_queue_purge+0xf4/0x100 [ 30.858631] [] ? sock_release+0x1c0/0x1c0 [ 30.864463] [] pppol2tp_release+0x1fb/0x2e0 [ 30.870449] [] sock_release+0x96/0x1c0 [ 30.875979] [] sock_close+0x16/0x20 [ 30.881252] [] __fput+0x263/0x700 [ 30.886354] [] ____fput+0x15/0x20 [ 30.891441] [] task_work_run+0x10c/0x180 [ 30.897140] [] get_signal+0x1133/0x1450 [ 30.902749] [] do_signal+0x87/0x19f0 [ 30.908107] [] ? retint_kernel+0x2d/0x2d [ 30.913823] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 30.920681] [] ? setup_sigcontext+0x7d0/0x7d0 [ 30.926823] [] ? check_preemption_disabled+0x3b/0x170 [ 30.933653] [] ? kick_process+0xed/0x170 [ 30.939363] [] ? task_work_add+0x8a/0xe0 [ 30.945152] [] ? fput+0xd2/0x140 [ 30.950161] [] ? exit_to_usermode_loop+0xac/0x120 [ 30.956745] [] exit_to_usermode_loop+0xe1/0x120 [ 30.963061] [] do_fast_syscall_32+0x5c3/0x870 [ 30.969219] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 30.975877] [] entry_SYSENTER_compat+0x90/0xa2 [ 30.982093] [ 30.983708] Allocated by task 4072: [ 30.987319] save_stack_trace+0x16/0x20 [ 30.991280] save_stack+0x43/0xd0 [ 30.994726] kasan_kmalloc+0xc7/0xe0 [ 30.998432] __kmalloc+0x11d/0x300 [ 31.001975] l2tp_session_create+0x38/0x16f0 [ 31.006371] pppol2tp_connect+0x10d7/0x18f0 [ 31.010684] SYSC_connect+0x1b8/0x300 [ 31.014481] SyS_connect+0x24/0x30 [ 31.018009] do_fast_syscall_32+0x2f7/0x870 [ 31.022320] entry_SYSENTER_compat+0x90/0xa2 [ 31.026701] [ 31.028312] Freed by task 4086: [ 31.031586] save_stack_trace+0x16/0x20 [ 31.035547] save_stack+0x43/0xd0 [ 31.038976] kasan_slab_free+0x72/0xc0 [ 31.042846] kfree+0xfb/0x310 [ 31.045936] l2tp_session_free+0x166/0x200 [ 31.050176] l2tp_tunnel_closeall+0x284/0x350 [ 31.054658] l2tp_udp_encap_destroy+0x87/0xe0 [ 31.059149] udpv6_destroy_sock+0xb1/0xd0 [ 31.063294] sk_common_release+0x6d/0x300 [ 31.067430] udp_lib_close+0x15/0x20 [ 31.071133] inet_release+0xff/0x1d0 [ 31.074838] inet6_release+0x50/0x70 [ 31.078533] sock_release+0x96/0x1c0 [ 31.082237] sock_close+0x16/0x20 [ 31.085684] __fput+0x263/0x700 [ 31.088943] ____fput+0x15/0x20 [ 31.092212] task_work_run+0x10c/0x180 [ 31.096174] exit_to_usermode_loop+0xfc/0x120 [ 31.100648] do_fast_syscall_32+0x5c3/0x870 [ 31.104954] entry_SYSENTER_compat+0x90/0xa2 [ 31.109342] [ 31.110951] The buggy address belongs to the object at ffff8801da1d5180 [ 31.110951] which belongs to the cache kmalloc-512 of size 512 [ 31.123610] The buggy address is located 0 bytes inside of [ 31.123610] 512-byte region [ffff8801da1d5180, ffff8801da1d5380) [ 31.135478] The buggy address belongs to the page: [ 31.140416] page:ffffea0007687500 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 31.150606] flags: 0x8000000000004080(slab|head) [ 31.155339] page dumped because: kasan: bad access detected [ 31.161032] [ 31.162654] Memory state around the buggy address: [ 31.167852] ffff8801da1d5080: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc [ 31.175230] ffff8801da1d5100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 31.182589] >ffff8801da1d5180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 31.189939] ^ [ 31.193304] ffff8801da1d5200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 31.200655] ffff8801da1d5280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 31.207997] ================================================================== [ 31.215345] Disabling lock debugging due to kernel taint [ 31.221165] Kernel panic - not syncing: panic_on_warn set ... [ 31.221165] [ 31.228532] CPU: 0 PID: 4072 Comm: syz-executor6 Tainted: G B 4.9.99-gc2f9bce #25 [ 31.237271] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.246622] ffff8801d7d3f988 ffffffff81eb0f09 ffffffff843c5065 00000000ffffffff [ 31.254665] 0000000000000000 0000000000000000 ffffffff8300fbe0 ffff8801d7d3fa48 [ 31.262843] ffffffff8141f855 0000000041b58ab3 ffffffff843b8768 ffffffff8141f696 [ 31.270907] Call Trace: [ 31.273489] [] dump_stack+0xc1/0x128 [ 31.278875] [] ? sock_release+0x1c0/0x1c0 [ 31.284690] [] panic+0x1bf/0x3bc [ 31.289704] [] ? add_taint.cold.6+0x16/0x16 [ 31.295691] [] ? ___preempt_schedule+0x16/0x18 [ 31.302361] [] kasan_end_report+0x47/0x4f [ 31.308166] [] kasan_report.cold.6+0x76/0x2fe [ 31.314312] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 31.321213] [] __asan_report_load4_noabort+0x14/0x20 [ 31.327960] [] l2tp_session_queue_purge+0xf4/0x100 [ 31.334531] [] ? sock_release+0x1c0/0x1c0 [ 31.340329] [] pppol2tp_release+0x1fb/0x2e0 [ 31.346288] [] sock_release+0x96/0x1c0 [ 31.351820] [] sock_close+0x16/0x20 [ 31.357090] [] __fput+0x263/0x700 [ 31.362200] [] ____fput+0x15/0x20 [ 31.367904] [] task_work_run+0x10c/0x180 [ 31.373602] [] get_signal+0x1133/0x1450 [ 31.379214] [] do_signal+0x87/0x19f0 [ 31.384565] [] ? retint_kernel+0x2d/0x2d [ 31.390268] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 31.397126] [] ? setup_sigcontext+0x7d0/0x7d0 [ 31.403301] [] ? check_preemption_disabled+0x3b/0x170 [ 31.410134] [] ? kick_process+0xed/0x170 [ 31.415947] [] ? task_work_add+0x8a/0xe0 [ 31.421650] [] ? fput+0xd2/0x140 [ 31.426663] [] ? exit_to_usermode_loop+0xac/0x120 [ 31.433151] [] exit_to_usermode_loop+0xe1/0x120 [ 31.439454] [] do_fast_syscall_32+0x5c3/0x870 [ 31.445600] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 31.452266] [] entry_SYSENTER_compat+0x90/0xa2 [ 31.459060] Dumping ftrace buffer: [ 31.462600] (ftrace buffer empty) [ 31.466306] Kernel Offset: disabled [ 31.469918] Rebooting in 86400 seconds..