[....] Starting enhanced syslogd: rsyslogd[ 12.971852] audit: type=1400 audit(1518296469.834:4): avc: denied { syslog } for pid=3522 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 '10.128.0.44' (ECDSA) to the list of known hosts. executing program executing program executing program executing program syzkaller login: [ 33.123329] ================================================================== [ 33.130717] BUG: KASAN: use-after-free in do_raw_spin_lock+0x1b9/0x1e0 [ 33.137363] Write of size 4 at addr ffff8801d89487e0 by task syzkaller256349/3682 [ 33.144966] [ 33.146577] CPU: 1 PID: 3682 Comm: syzkaller256349 Not tainted 4.9.80-g8a174b47 #39 [ 33.154341] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.163668] ffff8801d882fc08 ffffffff81d94be9 ffffea0007625200 ffff8801d89487e0 [ 33.171663] 0000000000000001 ffff8801d89487e0 ffff8801d8948900 ffff8801d882fc40 [ 33.179670] ffffffff8153e113 ffff8801d89487e0 0000000000000004 0000000000000001 [ 33.187658] Call Trace: [ 33.190223] [] dump_stack+0xc1/0x128 [ 33.195563] [] print_address_description+0x73/0x280 [ 33.202212] [] kasan_report+0x275/0x360 [ 33.207812] [] ? do_raw_spin_lock+0x1b9/0x1e0 [ 33.213932] [] __asan_report_store4_noabort+0x17/0x20 [ 33.220746] [] do_raw_spin_lock+0x1b9/0x1e0 [ 33.226695] [] _raw_spin_lock_irqsave+0x56/0x70 [ 33.232988] [] ? skb_dequeue+0x22/0x180 [ 33.238589] [] skb_dequeue+0x22/0x180 [ 33.244182] [] l2tp_session_queue_purge+0xab/0x100 [ 33.250771] [] ? sock_release+0x1e0/0x1e0 [ 33.256555] [] pppol2tp_release+0x1ff/0x2e0 [ 33.262512] [] sock_release+0x8d/0x1e0 [ 33.268038] [] sock_close+0x16/0x20 [ 33.273300] [] __fput+0x28c/0x6e0 [ 33.278391] [] ____fput+0x15/0x20 [ 33.283487] [] task_work_run+0x115/0x190 [ 33.289177] [] exit_to_usermode_loop+0xfc/0x120 [ 33.295475] [] do_fast_syscall_32+0x5de/0x890 [ 33.301598] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 33.308246] [] entry_SYSENTER_compat+0x74/0x83 [ 33.314456] [ 33.316066] Allocated by task 3681: [ 33.319676] save_stack_trace+0x16/0x20 [ 33.323625] save_stack+0x43/0xd0 [ 33.327050] kasan_kmalloc+0xad/0xe0 [ 33.330756] __kmalloc+0x11d/0x310 [ 33.334273] l2tp_session_create+0x38/0x1770 [ 33.338652] pppol2tp_connect+0x10fe/0x18f0 [ 33.342963] SYSC_connect+0x1b6/0x310 [ 33.346746] SyS_connect+0x24/0x30 [ 33.350266] do_fast_syscall_32+0x2f7/0x890 [ 33.354563] entry_SYSENTER_compat+0x74/0x83 [ 33.358944] [ 33.360556] Freed by task 3681: [ 33.363811] save_stack_trace+0x16/0x20 [ 33.367772] save_stack+0x43/0xd0 [ 33.371206] kasan_slab_free+0x72/0xc0 [ 33.375074] kfree+0x103/0x300 [ 33.378242] l2tp_session_free+0x166/0x200 [ 33.382451] l2tp_tunnel_closeall+0x26c/0x3a0 [ 33.386918] l2tp_udp_encap_destroy+0x87/0xe0 [ 33.391391] udpv6_destroy_sock+0xb1/0xd0 [ 33.395520] sk_common_release+0x6b/0x2f0 [ 33.399646] udp_lib_close+0x15/0x20 [ 33.403336] inet_release+0xfa/0x1d0 [ 33.407028] inet6_release+0x50/0x70 [ 33.410725] sock_release+0x8d/0x1e0 [ 33.414418] sock_close+0x16/0x20 [ 33.417859] __fput+0x28c/0x6e0 [ 33.421120] ____fput+0x15/0x20 [ 33.424386] task_work_run+0x115/0x190 [ 33.428248] exit_to_usermode_loop+0xfc/0x120 [ 33.432724] do_fast_syscall_32+0x5de/0x890 [ 33.437022] entry_SYSENTER_compat+0x74/0x83 [ 33.441401] [ 33.443001] The buggy address belongs to the object at ffff8801d8948780 [ 33.443001] which belongs to the cache kmalloc-512 of size 512 [ 33.455635] The buggy address is located 96 bytes inside of [ 33.455635] 512-byte region [ffff8801d8948780, ffff8801d8948980) [ 33.467396] The buggy address belongs to the page: [ 33.472306] page:ffffea0007625200 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 33.482563] flags: 0x8000000000004080(slab|head) [ 33.487288] page dumped because: kasan: bad access detected [ 33.492969] [ 33.494575] Memory state around the buggy address: [ 33.499476] ffff8801d8948680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 33.506813] ffff8801d8948700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 33.514150] >ffff8801d8948780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 33.521485] ^ [ 33.527953] ffff8801d8948800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 33.535306] ffff8801d8948880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 33.542641] ================================================================== [ 33.549984] Disabling lock debugging due to kernel taint [ 33.555432] Kernel panic - not syncing: panic_on_warn set ... [ 33.555432] [ 33.562771] CPU: 1 PID: 3682 Comm: syzkaller256349 Tainted: G B 4.9.80-g8a174b47 #39 [ 33.571758] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.581089] ffff8801d882fb60 ffffffff81d94be9 ffffffff841970c7 ffff8801d882fc38 [ 33.589083] 0000000000000000 ffff8801d89487e0 ffff8801d8948900 ffff8801d882fc28 [ 33.597069] ffffffff8142f5c1 0000000041b58ab3 ffffffff8418ab38 ffffffff8142f405 [ 33.605055] Call Trace: [ 33.607622] [] dump_stack+0xc1/0x128 [ 33.612975] [] panic+0x1bc/0x3a8 [ 33.617976] [] ? percpu_up_read_preempt_enable.constprop.53+0xd7/0xd7 [ 33.626180] [] kasan_end_report+0x50/0x50 [ 33.631962] [] kasan_report+0x167/0x360 [ 33.637576] [] ? do_raw_spin_lock+0x1b9/0x1e0 [ 33.643717] [] __asan_report_store4_noabort+0x17/0x20 [ 33.650555] [] do_raw_spin_lock+0x1b9/0x1e0 [ 33.656510] [] _raw_spin_lock_irqsave+0x56/0x70 [ 33.662808] [] ? skb_dequeue+0x22/0x180 [ 33.668431] [] skb_dequeue+0x22/0x180 [ 33.668439] [] l2tp_session_queue_purge+0xab/0x100 [ 33.668444] [] ? sock_release+0x1e0/0x1e0 [ 33.668456] [] pppol2tp_release+0x1ff/0x2e0 [ 33.668460] [] sock_release+0x8d/0x1e0 [ 33.668463] [] sock_close+0x16/0x20 [ 33.668468] [] __fput+0x28c/0x6e0 [ 33.668471] [] ____fput+0x15/0x20 [ 33.668477] [] task_work_run+0x115/0x190 [ 33.668482] [] exit_to_usermode_loop+0xfc/0x120 [ 33.668486] [] do_fast_syscall_32+0x5de/0x890 [ 33.668489] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 33.668495] [] entry_SYSENTER_compat+0x74/0x83 [ 33.674318] Dumping ftrace buffer: [ 33.674322] (ftrace buffer empty) [ 33.674324] Kernel Offset: disabled [ 33.755755] Rebooting in 86400 seconds..