[....] Starting enhanced syslogd: rsyslogd[ 10.371481] audit: type=1400 audit(1516452648.347:4): avc: denied { syslog } for pid=3173 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[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Starting mcstransd: [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.15.230' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 21.616951] ================================================================== [ 21.618109] BUG: KASAN: use-after-free in ip6_xmit+0x1bc7/0x1bd0 [ 21.618951] Read of size 8 at addr ffff8801d86ea298 by task syzkaller756324/3328 [ 21.619972] [ 21.620221] CPU: 1 PID: 3328 Comm: syzkaller756324 Not tainted 4.9.77-ge12a9c4 #18 [ 21.621281] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.622516] ffff8801c7d57690 ffffffff81d941c9 ffffea000761ba80 ffff8801d86ea298 [ 21.623775] 0000000000000000 ffff8801d86ea298 ffff8801c962b1e4 ffff8801c7d576c8 [ 21.625032] ffffffff8153db93 ffff8801d86ea298 0000000000000008 0000000000000000 [ 21.626352] Call Trace: [ 21.626831] [] dump_stack+0xc1/0x128 [ 21.627569] [] print_address_description+0x73/0x280 [ 21.628450] [] kasan_report+0x275/0x360 [ 21.629218] [] ? ip6_xmit+0x1bc7/0x1bd0 [ 21.629987] [] __asan_report_load8_noabort+0x14/0x20 [ 21.630880] [] ip6_xmit+0x1bc7/0x1bd0 [ 21.631620] [] ? save_stack_trace+0x16/0x20 [ 21.632431] [] ? save_trace+0xe0/0x270 [ 21.633166] [] ? ip6_finish_output2+0x1d20/0x1d20 [ 21.634025] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 21.634988] [] ? __lock_is_held+0xa1/0xf0 [ 21.635780] [] ? ipv4_dst_check+0x111/0x160 [ 21.636658] [] ? __sk_dst_check+0x10e/0x240 [ 21.637506] [] inet6_csk_xmit+0x27d/0x4d0 [ 21.643275] [] ? inet6_csk_xmit+0x100/0x4d0 [ 21.649229] [] ? inet6_csk_update_pmtu+0x160/0x160 [ 21.655803] [] l2tp_xmit_skb+0xcdc/0xf50 [ 21.661488] [] pppol2tp_sendmsg+0x5c0/0x7a0 [ 21.667440] [] ? selinux_socket_sendmsg+0x3f/0x50 [ 21.673912] [] ? pppol2tp_release+0x2e0/0x2e0 [ 21.680043] [] sock_sendmsg+0xca/0x110 [ 21.685567] [] ___sys_sendmsg+0x6d1/0x7e0 [ 21.691340] [] ? copy_msghdr_from_user+0x550/0x550 [ 21.697892] [] ? __lru_cache_add+0x187/0x250 [ 21.703924] [] ? do_huge_pmd_anonymous_page+0xb05/0x10d0 [ 21.711008] [] ? _raw_spin_unlock+0x2c/0x50 [ 21.716967] [] ? do_huge_pmd_anonymous_page+0x2d4/0x10d0 [ 21.724048] [] ? handle_mm_fault+0x6ee/0x2530 [ 21.730266] [] ? __pmd_alloc+0x410/0x410 [ 21.735944] [] ? __fdget+0x18/0x20 [ 21.741117] [] __sys_sendmsg+0xd6/0x190 [ 21.746714] [] ? SyS_shutdown+0x1b0/0x1b0 [ 21.752484] [] ? __do_page_fault+0x5ec/0xd40 [ 21.758512] [] ? __do_page_fault+0x3bd/0xd40 [ 21.764549] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 21.771363] [] SyS_sendmsg+0x2d/0x50 [ 21.776702] [] entry_SYSCALL_64_fastpath+0x29/0xe8 [ 21.783251] [ 21.784848] Allocated by task 3308: [ 21.788448] save_stack_trace+0x16/0x20 [ 21.792398] save_stack+0x43/0xd0 [ 21.795820] kasan_kmalloc+0xad/0xe0 [ 21.799503] kasan_slab_alloc+0x12/0x20 [ 21.803445] kmem_cache_alloc+0xba/0x290 [ 21.807476] dst_alloc+0x11f/0x1a0 [ 21.810987] rt_dst_alloc+0x78/0x430 [ 21.814672] __ip_route_output_key_hash+0xa4e/0x23e0 [ 21.819758] __ip4_datagram_connect+0xa17/0x1160 [ 21.824490] __ip6_datagram_connect+0x6f9/0xdf0 [ 21.829149] ip6_datagram_connect+0x2f/0x50 [ 21.833443] inet_dgram_connect+0x16b/0x1f0 [ 21.837738] SYSC_connect+0x1b6/0x310 [ 21.841514] SyS_connect+0x24/0x30 [ 21.845027] entry_SYSCALL_64_fastpath+0x29/0xe8 [ 21.849751] [ 21.851347] Freed by task 17: [ 21.854429] save_stack_trace+0x16/0x20 [ 21.858380] save_stack+0x43/0xd0 [ 21.861806] kasan_slab_free+0x72/0xc0 [ 21.865663] kmem_cache_free+0xc7/0x300 [ 21.869613] dst_destroy+0x1fd/0x360 [ 21.873298] dst_destroy_rcu+0x15/0x40 [ 21.877159] rcu_process_callbacks+0x898/0x1300 [ 21.881804] __do_softirq+0x206/0x951 [ 21.885573] [ 21.887173] The buggy address belongs to the object at ffff8801d86ea280 [ 21.887173] which belongs to the cache ip_dst_cache of size 216 [ 21.899906] The buggy address is located 24 bytes inside of [ 21.899906] 216-byte region [ffff8801d86ea280, ffff8801d86ea358) [ 21.911675] The buggy address belongs to the page: [ 21.916581] page:ffffea000761ba80 count:1 mapcount:0 mapping: (null) index:0x0 [ 21.924825] flags: 0x8000000000000080(slab) [ 21.929114] page dumped because: kasan: bad access detected [ 21.934795] [ 21.936392] Memory state around the buggy address: [ 21.941298] ffff8801d86ea180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 21.948643] ffff8801d86ea200: 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc [ 21.955982] >ffff8801d86ea280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 21.963314] ^ [ 21.967447] ffff8801d86ea300: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc [ 21.974793] ffff8801d86ea380: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 [ 21.982131] ================================================================== [ 21.989458] Disabling lock debugging due to kernel taint [ 21.994917] Kernel panic - not syncing: panic_on_warn set ... [ 21.994917] [ 22.002268] CPU: 1 PID: 3328 Comm: syzkaller756324 Tainted: G B 4.9.77-ge12a9c4 #18 [ 22.011161] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 22.020493] ffff8801c7d575e8 ffffffff81d941c9 ffffffff841970ff ffff8801c7d576c0 [ 22.028481] 0000000000000000 ffff8801d86ea298 ffff8801c962b1e4 ffff8801c7d576b0 [ 22.036448] ffffffff8142f3c1 0000000041b58ab3 ffffffff8418ab70 ffffffff8142f205 [ 22.044422] Call Trace: [ 22.046984] [] dump_stack+0xc1/0x128 [ 22.052319] [] panic+0x1bc/0x3a8 [ 22.057323] [] ? percpu_up_read_preempt_enable.constprop.53+0xd7/0xd7 [ 22.065539] [] kasan_end_report+0x50/0x50 [ 22.071312] [] kasan_report+0x167/0x360 [ 22.076931] [] ? ip6_xmit+0x1bc7/0x1bd0 [ 22.082559] [] __asan_report_load8_noabort+0x14/0x20 [ 22.089294] [] ip6_xmit+0x1bc7/0x1bd0 [ 22.094716] [] ? save_stack_trace+0x16/0x20 [ 22.100659] [] ? save_trace+0xe0/0x270 [ 22.106168] [] ? ip6_finish_output2+0x1d20/0x1d20 [ 22.112632] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 22.119624] [] ? __lock_is_held+0xa1/0xf0 [ 22.125397] [] ? ipv4_dst_check+0x111/0x160 [ 22.131346] [] ? __sk_dst_check+0x10e/0x240 [ 22.137297] [] inet6_csk_xmit+0x27d/0x4d0 [ 22.143071] [] ? inet6_csk_xmit+0x100/0x4d0 [ 22.149025] [] ? inet6_csk_update_pmtu+0x160/0x160 [ 22.155578] [] l2tp_xmit_skb+0xcdc/0xf50 [ 22.161276] [] pppol2tp_sendmsg+0x5c0/0x7a0 [ 22.167225] [] ? selinux_socket_sendmsg+0x3f/0x50 [ 22.173701] [] ? pppol2tp_release+0x2e0/0x2e0 [ 22.179826] [] sock_sendmsg+0xca/0x110 [ 22.185335] [] ___sys_sendmsg+0x6d1/0x7e0 [ 22.191107] [] ? copy_msghdr_from_user+0x550/0x550 [ 22.198610] [] ? __lru_cache_add+0x187/0x250 [ 22.204640] [] ? do_huge_pmd_anonymous_page+0xb05/0x10d0 [ 22.211731] [] ? _raw_spin_unlock+0x2c/0x50 [ 22.217678] [] ? do_huge_pmd_anonymous_page+0x2d4/0x10d0 [ 22.224750] [] ? handle_mm_fault+0x6ee/0x2530 [ 22.230866] [] ? __pmd_alloc+0x410/0x410 [ 22.236551] [] ? __fdget+0x18/0x20 [ 22.241718] [] __sys_sendmsg+0xd6/0x190 [ 22.247313] [] ? SyS_shutdown+0x1b0/0x1b0 [ 22.253086] [] ? __do_page_fault+0x5ec/0xd40 [ 22.259117] [] ? __do_page_fault+0x3bd/0xd40 [ 22.265161] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 22.271973] [] SyS_sendmsg+0x2d/0x50 [ 22.277308] [] entry_SYSCALL_64_fastpath+0x29/0xe8 [ 22.284309] Dumping ftrace buffer: [ 22.287827] (ftrace buffer empty) [ 22.291510] Kernel Offset: disabled [ 22.295110] Rebooting in 86400 seconds..