[....] Starting enhanced syslogd: rsyslogd[ 12.978255] audit: type=1400 audit(1519431947.370:4): avc: denied { syslog } for pid=3650 comm="rsyslogd" capability=34 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=capability2 permissive=1 [?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. Starting mcstransd: [....] Starting file context maintaining daemon: restorecond[?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 '10.128.15.200' (ECDSA) to the list of known hosts. net.ipv6.conf.syz0.accept_dad = 0 net.ipv6.conf.syz0.router_solicitations = 0 syzkaller login: [ 26.186200] IPVS: Creating netns size=2536 id=1 RTNETLINK answers: Operation not supported RTNETLINK answers: Operation not supported RTNETLINK answers: Operation not supported RTNETLINK answers: Operation not supported RTNETLINK answers: File exists RTNETLINK answers: File exists RTNETLINK answers: Operation not supported Cannot find device "bridge0" Cannot find device "bridge0" Cannot find device "bridge0" Cannot find device "bridge0" Cannot find device "vcan0" Cannot find device "vcan0" Cannot find device "vcan0" Cannot find device "vcan0" RTNETLINK answers: Operation not supported Cannot find device "gre0" Cannot find device "gre0" Cannot find device "gre0" Cannot find device "gre0" Cannot find device "gretap0" Cannot find device "gretap0" Cannot find device "gretap0" Cannot find device "gretap0" Cannot find device "ip_vti0" Cannot find device "ip_vti0" Cannot find device "ip_vti0" Cannot find device "ip_vti0" Cannot find device "ip6_vti0" Cannot find device "ip6_vti0" Cannot find device "ip6_vti0" Cannot find device "ip6_vti0" Cannot find device "ip6tnl0" Cannot find device "ip6tnl0" Cannot find device "ip6tnl0" Cannot find device "ip6tnl0" Cannot find device "ip6gre0" Cannot find device "ip6gre0" Cannot find device "ip6gre0" Cannot find device "ip6gre0" Cannot find device "ip6gretap0" Cannot find device "ip6gretap0" Cannot find device "ip6gretap0" Cannot find device "ip6gretap0" Cannot find device "erspan0" Cannot find device "erspan0" Cannot find device "erspan0" Cannot find device "erspan0" Cannot find device "bond0" Cannot find device "bond0" Cannot find device "bond0" Cannot find device "bond0" Cannot find device "veth0" Cannot find device "veth0" Cannot find device "veth0" Cannot find device "veth0" Cannot find device "veth1" Cannot find device "veth1" Cannot find device "veth1" Cannot find device "veth1" executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 27.133862] ================================================================== [ 27.141243] BUG: KASAN: use-after-free in pppol2tp_session_destruct+0xe9/0x110 [ 27.148583] Read of size 4 at addr ffff8801b57d9180 by task syzkaller545216/4075 [ 27.156082] [ 27.157681] CPU: 0 PID: 4075 Comm: syzkaller545216 Not tainted 4.9.83-g72766d7 #42 [ 27.165357] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.174685] ffff8801d5167c28 ffffffff81d95149 ffffea0006d5f600 ffff8801b57d9180 [ 27.182656] 0000000000000000 ffff8801b57d9180 ffffffff82ed59f0 ffff8801d5167c60 [ 27.190624] ffffffff8153e213 ffff8801b57d9180 0000000000000004 0000000000000000 [ 27.198602] Call Trace: [ 27.201163] [] dump_stack+0xc1/0x128 [ 27.206500] [] ? sock_release+0x1e0/0x1e0 [ 27.212276] [] print_address_description+0x73/0x280 [ 27.218913] [] ? sock_release+0x1e0/0x1e0 [ 27.224682] [] kasan_report+0x275/0x360 [ 27.230282] [] ? pppol2tp_session_destruct+0xe9/0x110 [ 27.237091] [] __asan_report_load4_noabort+0x14/0x20 [ 27.243829] [] pppol2tp_session_destruct+0xe9/0x110 [ 27.250469] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.256755] [] __sk_destruct+0x53/0x570 [ 27.262346] [] ? sock_release+0x1e0/0x1e0 [ 27.268112] [] sk_destruct+0x47/0x80 [ 27.273451] [] __sk_free+0x57/0x230 [ 27.278712] [] sk_free+0x23/0x30 [ 27.283699] [] pppol2tp_release+0x23d/0x2e0 [ 27.289639] [] sock_release+0x8d/0x1e0 [ 27.295142] [] sock_close+0x16/0x20 [ 27.300393] [] __fput+0x28c/0x6e0 [ 27.305469] [] ____fput+0x15/0x20 [ 27.310540] [] task_work_run+0x115/0x190 [ 27.316218] [] exit_to_usermode_loop+0xfc/0x120 [ 27.322506] [] do_syscall_64+0x36f/0x490 [ 27.328187] [] entry_SYSCALL_64_after_swapgs+0x47/0xc5 [ 27.335077] [ 27.336677] Allocated by task 4075: [ 27.340273] save_stack_trace+0x16/0x20 [ 27.344214] save_stack+0x43/0xd0 [ 27.347636] kasan_kmalloc+0xad/0xe0 [ 27.351318] __kmalloc+0x11d/0x310 [ 27.354823] l2tp_session_create+0x38/0x1770 [ 27.359198] pppol2tp_connect+0x10fe/0x18f0 [ 27.363485] SYSC_connect+0x1b6/0x310 [ 27.367252] SyS_connect+0x24/0x30 [ 27.370759] do_syscall_64+0x1a4/0x490 [ 27.374614] entry_SYSCALL_64_after_swapgs+0x47/0xc5 [ 27.379684] [ 27.381281] Freed by task 4076: [ 27.384527] save_stack_trace+0x16/0x20 [ 27.388470] save_stack+0x43/0xd0 [ 27.391890] kasan_slab_free+0x72/0xc0 [ 27.395749] kfree+0x103/0x300 [ 27.398920] l2tp_session_free+0x166/0x200 [ 27.403131] l2tp_tunnel_closeall+0x26c/0x3a0 [ 27.407594] l2tp_udp_encap_destroy+0x87/0xe0 [ 27.412057] udpv6_destroy_sock+0xb1/0xd0 [ 27.416174] sk_common_release+0x6b/0x2f0 [ 27.420289] udp_lib_close+0x15/0x20 [ 27.423972] inet_release+0xfa/0x1d0 [ 27.427654] inet6_release+0x50/0x70 [ 27.431336] sock_release+0x8d/0x1e0 [ 27.435018] sock_close+0x16/0x20 [ 27.438441] __fput+0x28c/0x6e0 [ 27.441687] ____fput+0x15/0x20 [ 27.444934] task_work_run+0x115/0x190 [ 27.448787] exit_to_usermode_loop+0xfc/0x120 [ 27.453256] do_syscall_64+0x36f/0x490 [ 27.457122] entry_SYSCALL_64_after_swapgs+0x47/0xc5 [ 27.462192] [ 27.463792] The buggy address belongs to the object at ffff8801b57d9180 [ 27.463792] which belongs to the cache kmalloc-512 of size 512 [ 27.476422] The buggy address is located 0 bytes inside of [ 27.476422] 512-byte region [ffff8801b57d9180, ffff8801b57d9380) [ 27.488086] The buggy address belongs to the page: [ 27.492986] page:ffffea0006d5f600 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 27.503165] flags: 0x8000000000004080(slab|head) [ 27.507887] page dumped because: kasan: bad access detected [ 27.513564] [ 27.515159] Memory state around the buggy address: [ 27.520056] ffff8801b57d9080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 27.527384] ffff8801b57d9100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 27.534711] >ffff8801b57d9180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 27.542037] ^ [ 27.545371] ffff8801b57d9200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 27.553054] ffff8801b57d9280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 27.560381] ================================================================== [ 27.567706] Disabling lock debugging due to kernel taint [ 27.573861] Kernel panic - not syncing: panic_on_warn set ... [ 27.573861] [ 27.581227] CPU: 0 PID: 4075 Comm: syzkaller545216 Tainted: G B 4.9.83-g72766d7 #42 [ 27.590118] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.599445] ffff8801d5167b80 ffffffff81d95149 ffffffff8419777f ffff8801d5167c58 [ 27.607414] 0000000000000000 ffff8801b57d9180 ffffffff82ed59f0 ffff8801d5167c48 [ 27.615389] ffffffff8142f6c1 0000000041b58ab3 ffffffff8418b1f0 ffffffff8142f505 [ 27.623356] Call Trace: [ 27.625918] [] dump_stack+0xc1/0x128 [ 27.631251] [] ? sock_release+0x1e0/0x1e0 [ 27.637019] [] panic+0x1bc/0x3a8 [ 27.642007] [] ? percpu_up_read_preempt_enable.constprop.53+0xd7/0xd7 [ 27.650203] [] ? preempt_schedule+0x25/0x30 [ 27.656143] [] ? ___preempt_schedule+0x16/0x18 [ 27.662346] [] kasan_end_report+0x50/0x50 [ 27.668111] [] kasan_report+0x167/0x360 [ 27.673707] [] ? pppol2tp_session_destruct+0xe9/0x110 [ 27.680514] [] __asan_report_load4_noabort+0x14/0x20 [ 27.687232] [] pppol2tp_session_destruct+0xe9/0x110 [ 27.693864] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.700152] [] __sk_destruct+0x53/0x570 [ 27.705742] [] ? sock_release+0x1e0/0x1e0 [ 27.711507] [] sk_destruct+0x47/0x80 [ 27.716840] [] __sk_free+0x57/0x230 [ 27.722085] [] sk_free+0x23/0x30 [ 27.727077] [] pppol2tp_release+0x23d/0x2e0 [ 27.733016] [] sock_release+0x8d/0x1e0 [ 27.738518] [] sock_close+0x16/0x20 [ 27.743764] [] __fput+0x28c/0x6e0 [ 27.748834] [] ____fput+0x15/0x20 [ 27.753909] [] task_work_run+0x115/0x190 [ 27.759587] [] exit_to_usermode_loop+0xfc/0x120 [ 27.765875] [] do_syscall_64+0x36f/0x490 [ 27.771553] [] entry_SYSCALL_64_after_swapgs+0x47/0xc5 [ 27.778842] Dumping ftrace buffer: [ 27.782351] (ftrace buffer empty) [ 27.786030] Kernel Offset: disabled [ 27.789628] Rebooting in 86400 seconds..