[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 19.503531] random: sshd: uninitialized urandom read (32 bytes read, 31 bits of entropy available) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.577942] random: sshd: uninitialized urandom read (32 bytes read, 35 bits of entropy available) [ 23.974874] random: sshd: uninitialized urandom read (32 bytes read, 35 bits of entropy available) [ 24.965481] random: nonblocking pool is initialized Warning: Permanently added '10.128.10.13' (ECDSA) to the list of known hosts. 2018/06/21 00:50:32 parsed 1 programs 2018/06/21 00:50:34 executed programs: 0 [ 40.701789] IPVS: Creating netns size=2552 id=1 [ 41.006825] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 41.025165] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 41.120624] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 41.135630] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 41.235621] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 41.251575] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 41.268287] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 41.287118] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 42.188265] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 42.236104] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready 2018/06/21 00:50:39 executed programs: 78 [ 46.644205] ================================================================== [ 46.651676] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 46.658926] Read of size 4 at addr ffff8801cd657180 by task syz-executor0/4792 [ 46.666262] [ 46.667869] CPU: 0 PID: 4792 Comm: syz-executor0 Not tainted 4.4.138-g226f96b #61 [ 46.675547] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 46.684873] 0000000000000000 05745fad912c1808 ffff8801d39afad8 ffffffff81e0ed0d [ 46.692867] ffffea0007359580 ffff8801cd657180 0000000000000000 ffff8801cd657180 [ 46.700855] ffffffff82f1a2b0 ffff8801d39afb10 ffffffff81515a16 ffff8801cd657180 [ 46.708876] Call Trace: [ 46.711454] [] dump_stack+0xc1/0x124 [ 46.716802] [] ? sock_release+0x1c0/0x1c0 [ 46.722576] [] print_address_description+0x6c/0x216 [ 46.729214] [] ? sock_release+0x1c0/0x1c0 [ 46.734995] [] kasan_report.cold.7+0x175/0x2f7 [ 46.741201] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 46.747947] [] __asan_report_load4_noabort+0x14/0x20 [ 46.754675] [] l2tp_session_queue_purge+0xf4/0x100 [ 46.761231] [] ? sock_release+0x1c0/0x1c0 [ 46.767007] [] pppol2tp_release+0x1ff/0x310 [ 46.772968] [] sock_release+0x96/0x1c0 [ 46.778478] [] sock_close+0x16/0x20 [ 46.783729] [] __fput+0x235/0x6f0 [ 46.788806] [] ____fput+0x15/0x20 [ 46.793887] [] task_work_run+0x10f/0x190 [ 46.799568] [] do_exit+0x9e5/0x26b0 [ 46.804818] [] ? handle_mm_fault+0x19d8/0x30b0 [ 46.811022] [] ? release_task.part.17+0x1200/0x1200 [ 46.817667] [] do_group_exit+0x111/0x330 [ 46.823357] [] ? do_group_exit+0x330/0x330 [ 46.829221] [] SyS_exit_group+0x1d/0x20 [ 46.834836] [] do_fast_syscall_32+0x326/0x8b0 [ 46.840955] [] sysenter_flags_fixed+0xd/0x17 [ 46.846990] [ 46.848590] Allocated by task 4789: [ 46.852185] [] save_stack_trace+0x26/0x50 [ 46.858080] [] save_stack+0x43/0xd0 [ 46.863710] [] kasan_kmalloc+0xc7/0xe0 [ 46.869354] [] __kmalloc+0x124/0x310 [ 46.874820] [] l2tp_session_create+0x39/0x1030 [ 46.881154] [] pppol2tp_connect+0x10f0/0x1910 [ 46.887395] [] SYSC_connect+0x1b8/0x300 [ 46.893123] [] SyS_connect+0x24/0x30 [ 46.898573] [] do_fast_syscall_32+0x326/0x8b0 [ 46.904816] [] sysenter_flags_fixed+0xd/0x17 [ 46.910985] [ 46.912589] Freed by task 4780: [ 46.915835] [] save_stack_trace+0x26/0x50 [ 46.921733] [] save_stack+0x43/0xd0 [ 46.927103] [] kasan_slab_free+0x72/0xc0 [ 46.932920] [] kfree+0xf4/0x310 [ 46.937940] [] l2tp_session_free+0x170/0x200 [ 46.944097] [] l2tp_tunnel_closeall+0x2b9/0x350 [ 46.950513] [] l2tp_udp_encap_destroy+0x8b/0xf0 [ 46.956945] [] udpv6_destroy_sock+0xb1/0xd0 [ 46.963008] [] sk_common_release+0x6d/0x300 [ 46.969081] [] udp_lib_close+0x15/0x20 [ 46.974714] [] inet_release+0xff/0x1d0 [ 46.980351] [] inet6_release+0x50/0x70 [ 46.986004] [] sock_release+0x96/0x1c0 [ 46.991635] [] sock_close+0x16/0x20 [ 46.997003] [] __fput+0x235/0x6f0 [ 47.002364] [] ____fput+0x15/0x20 [ 47.007658] [] task_work_run+0x10f/0x190 [ 47.013461] [] do_exit+0x9e5/0x26b0 [ 47.018837] [] do_group_exit+0x111/0x330 [ 47.024642] [] SyS_exit_group+0x1d/0x20 [ 47.030358] [] do_fast_syscall_32+0x326/0x8b0 [ 47.036610] [] sysenter_flags_fixed+0xd/0x17 [ 47.042764] [ 47.044380] The buggy address belongs to the object at ffff8801cd657180 [ 47.044380] which belongs to the cache kmalloc-512 of size 512 [ 47.057022] The buggy address is located 0 bytes inside of [ 47.057022] 512-byte region [ffff8801cd657180, ffff8801cd657380) [ 47.068704] The buggy address belongs to the page: [ 47.104156] kasan: CONFIG_KASAN_INLINE enabled [ 47.108699] kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] PREEMPT SMP KASAN [ 47.121648] Dumping ftrace buffer: [ 47.125181] (ftrace buffer empty) [ 47.128888] Modules linked in: [ 47.132830] CPU: 1 PID: 3852 Comm: syz-executor0 Not tainted 4.4.138-g226f96b #61 [ 47.140454] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 47.149826] task: ffff8801d8d7b000 task.stack: ffff8800ad400000 [ 47.155888] RIP: 0010:[] [] kmem_cache_alloc+0x7e/0x2a0 [ 47.164695] RSP: 0000:ffff8800ad407b80 EFLAGS: 00010046 [ 47.170151] RAX: 4f5f4755425f4d56 RBX: 0000000000000000 RCX: 0000000000023960 [ 47.177424] RDX: 00000000000116c1 RSI: 00000000000116c1 RDI: 0000000000023960 [ 47.184872] RBP: ffff8800ad407bb0 R08: ffff8801d8d7b928 R09: 0000000000000001 [ 47.192148] R10: 0000000000000000 R11: ffff8801d8d7b000 R12: ffff8801d98fc8c0 [ 47.199422] R13: 4f5f4755425f4d56 R14: 0000000002280020 R15: ffffffff81154c01 [ 47.206700] FS: 0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000092c5900 [ 47.214934] CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 [ 47.220831] CR2: 000000008148ced7 CR3: 00000000baef1000 CR4: 00000000001606f0 [ 47.228128] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 47.235547] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 47.242825] Stack: [ 47.244979] ffff8801d8d7b000 ffff8801d8d7b000 ffffffff8448cf80 0000000000000001 [ 47.253064] 0000000002280020 000000000000000b ffff8800ad407bf0 ffffffff81154c01 [ 47.261157] ffffffff81154a20 ffff8801d8d7b000 0000000000000004 ffff8801d8d7b798 [ 47.269233] Call Trace: [ 47.271842] [] __sigqueue_alloc+0x1e1/0x400 [ 47.277829] [] ? trace_event_raw_event_signal_deliver+0x4a0/0x4a0 [ 47.285740] [] __send_signal+0x1a5/0x11b0 [ 47.291559] [] send_signal+0x4a/0xc0 [ 47.296941] [] force_sig_info+0x20a/0x310 [ 47.302762] [] force_sig_info_fault.constprop.23+0x158/0x1b0 [ 47.310227] [] ? is_prefetch.isra.20+0x390/0x390 [ 47.316744] [] ? spurious_fault_check+0xb0/0xb0 [ 47.323083] [] ? setup_sigcontext+0x780/0x780 [ 47.329249] [] ? __lock_is_held+0xa2/0xf0 [ 47.335072] [] __bad_area_nosemaphore+0x219/0x310 [ 47.341592] [] bad_area+0x66/0x80 [ 47.346717] [] __do_page_fault+0x767/0xa10 [ 47.352654] [] do_page_fault+0x27/0x30 [ 47.358208] [] page_fault+0x28/0x30 [ 47.363479] Code: 48 8b 70 08 48 39 f2 75 e7 4c 8b 28 4d 85 ed 0f 84 ec 00 00 00 49 63 44 24 20 49 8b 3c 24 4c 01 e8 40 f6 c7 0f 0f 85 11 01 00 00 <48> 8b 18 48 8d 4a 40 4c 89 e8 65 48 0f c7 0f 0f 94 c0 84 c0 74 [ 47.391336] RIP [] kmem_cache_alloc+0x7e/0x2a0 [ 47.397697] RSP [ 47.401322] ---[ end trace 42c741916279add5 ]--- [ 47.406075] Kernel panic - not syncing: Fatal exception [ 48.554053] Shutting down cpus with NMI [ 48.558694] Dumping ftrace buffer: [ 48.562237] (ftrace buffer empty) [ 48.565918] Kernel Offset: disabled [ 48.569518] Rebooting in 86400 seconds..