[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.401607] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.694016] random: sshd: uninitialized urandom read (32 bytes read) [ 19.149784] random: sshd: uninitialized urandom read (32 bytes read) [ 19.654691] random: sshd: uninitialized urandom read (32 bytes read) [ 21.074970] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.46' (ECDSA) to the list of known hosts. [ 26.463709] random: sshd: uninitialized urandom read (32 bytes read) 2018/08/08 15:47:35 parsed 1 programs [ 27.615000] random: cc1: uninitialized urandom read (8 bytes read) 2018/08/08 15:47:37 executed programs: 0 [ 28.715774] IPVS: Creating netns size=2536 id=1 [ 28.841943] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 28.855178] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 28.898234] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 28.909500] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 28.956958] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 28.968692] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 28.980743] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 28.994621] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 29.493023] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 29.518065] IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready [ 29.524399] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready [ 29.532331] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 29.715869] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 29.729900] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 29.754323] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 29.769716] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 29.792997] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 29.806211] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 29.829930] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 29.844720] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 29.870647] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 29.883745] l2tp_core: tunl 3: sockfd_lookup(fd=16) returned -9 [ 29.906095] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 29.991483] ================================================================== [ 29.998934] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 30.006208] Read of size 4 at addr ffff8801d7ca8000 by task syz-executor0/4206 [ 30.013543] [ 30.015161] CPU: 1 PID: 4206 Comm: syz-executor0 Not tainted 4.9.118-g47b77b8 #72 [ 30.022757] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.032098] ffff8801d51cfcb0 ffffffff81eb4b89 ffffea00075f2a00 ffff8801d7ca8000 [ 30.040106] 0000000000000000 ffff8801d7ca8000 ffffffff83015be0 ffff8801d51cfce8 [ 30.048276] ffffffff81567f29 ffff8801d7ca8000 0000000000000004 0000000000000000 [ 30.056304] Call Trace: [ 30.058879] [] dump_stack+0xc1/0x128 [ 30.064222] [] ? sock_release+0x1c0/0x1c0 [ 30.070002] [] print_address_description+0x6c/0x234 [ 30.076780] [] ? sock_release+0x1c0/0x1c0 [ 30.082575] [] kasan_report.cold.6+0x242/0x2fe [ 30.088797] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 30.095615] [] __asan_report_load4_noabort+0x14/0x20 [ 30.102396] [] l2tp_session_queue_purge+0xf4/0x100 [ 30.109007] [] ? sock_release+0x1c0/0x1c0 [ 30.114802] [] pppol2tp_release+0x1fb/0x2e0 [ 30.120895] [] sock_release+0x96/0x1c0 [ 30.126519] [] sock_close+0x16/0x20 [ 30.131780] [] __fput+0x263/0x700 [ 30.136873] [] ____fput+0x15/0x20 [ 30.141979] [] task_work_run+0x10c/0x180 [ 30.147672] [] exit_to_usermode_loop+0xfc/0x120 [ 30.154016] [] do_syscall_64+0x364/0x490 [ 30.159714] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.166615] [ 30.168220] Allocated by task 4212: [ 30.171880] save_stack_trace+0x16/0x20 [ 30.175839] save_stack+0x43/0xd0 [ 30.179271] kasan_kmalloc+0xc7/0xe0 [ 30.182967] __kmalloc+0x11d/0x300 [ 30.186488] l2tp_session_create+0x38/0x16f0 [ 30.190876] pppol2tp_connect+0x10d7/0x18f0 [ 30.195226] SYSC_connect+0x1b8/0x300 [ 30.199020] SyS_connect+0x24/0x30 [ 30.202539] do_syscall_64+0x1a6/0x490 [ 30.206410] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.211487] [ 30.213122] Freed by task 4212: [ 30.216382] save_stack_trace+0x16/0x20 [ 30.220337] save_stack+0x43/0xd0 [ 30.223770] kasan_slab_free+0x72/0xc0 [ 30.227641] kfree+0xfb/0x310 [ 30.230728] l2tp_session_free+0x166/0x200 [ 30.235050] l2tp_tunnel_closeall+0x284/0x350 [ 30.239526] l2tp_udp_encap_destroy+0x87/0xe0 [ 30.244004] udpv6_destroy_sock+0xb1/0xd0 [ 30.248136] sk_common_release+0x6d/0x300 [ 30.252276] udp_lib_close+0x15/0x20 [ 30.255974] inet_release+0xff/0x1d0 [ 30.259680] inet6_release+0x50/0x70 [ 30.263438] sock_release+0x96/0x1c0 [ 30.267155] sock_close+0x16/0x20 [ 30.270601] __fput+0x263/0x700 [ 30.273866] ____fput+0x15/0x20 [ 30.277137] task_work_run+0x10c/0x180 [ 30.281014] exit_to_usermode_loop+0xfc/0x120 [ 30.285490] do_syscall_64+0x364/0x490 [ 30.289366] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.294443] [ 30.296048] The buggy address belongs to the object at ffff8801d7ca8000 [ 30.296048] which belongs to the cache kmalloc-512 of size 512 [ 30.308823] The buggy address is located 0 bytes inside of [ 30.308823] 512-byte region [ffff8801d7ca8000, ffff8801d7ca8200) [ 30.320513] The buggy address belongs to the page: [ 30.325440] page:ffffea00075f2a00 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 30.335661] flags: 0x8000000000004080(slab|head) [ 30.340478] page dumped because: kasan: bad access detected [ 30.346165] [ 30.347768] Memory state around the buggy address: [ 30.352745] ffff8801d7ca7f00: fc fb fb fb fb fb fb fb fb fb fc fc fc fc fb fb [ 30.360095] ffff8801d7ca7f80: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc [ 30.367453] >ffff8801d7ca8000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 30.374808] ^ [ 30.378161] ffff8801d7ca8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 30.385501] ffff8801d7ca8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 30.392836] ================================================================== [ 30.400272] Disabling lock debugging due to kernel taint [ 30.406874] Kernel panic - not syncing: panic_on_warn set ... [ 30.406874] [ 30.414254] CPU: 1 PID: 4206 Comm: syz-executor0 Tainted: G B 4.9.118-g47b77b8 #72 [ 30.423081] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.432432] ffff8801d51cfc10 ffffffff81eb4b89 ffffffff843c8907 00000000ffffffff [ 30.440596] 0000000000000000 0000000000000001 ffffffff83015be0 ffff8801d51cfcd0 [ 30.448622] ffffffff81421c25 0000000041b58ab3 ffffffff843bbfe8 ffffffff81421a66 [ 30.456690] Call Trace: [ 30.459262] [] dump_stack+0xc1/0x128 [ 30.464627] [] ? sock_release+0x1c0/0x1c0 [ 30.470503] [] panic+0x1bf/0x3bc [ 30.475509] [] ? add_taint.cold.6+0x16/0x16 [ 30.481464] [] ? ___preempt_schedule+0x16/0x18 [ 30.487689] [] kasan_end_report+0x47/0x4f [ 30.493623] [] kasan_report.cold.6+0x76/0x2fe [ 30.499845] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 30.506740] [] __asan_report_load4_noabort+0x14/0x20 [ 30.513485] [] l2tp_session_queue_purge+0xf4/0x100 [ 30.520101] [] ? sock_release+0x1c0/0x1c0 [ 30.525901] [] pppol2tp_release+0x1fb/0x2e0 [ 30.531914] [] sock_release+0x96/0x1c0 [ 30.537492] [] sock_close+0x16/0x20 [ 30.542763] [] __fput+0x263/0x700 [ 30.547867] [] ____fput+0x15/0x20 [ 30.553027] [] task_work_run+0x10c/0x180 [ 30.558736] [] exit_to_usermode_loop+0xfc/0x120 [ 30.565131] [] do_syscall_64+0x364/0x490 [ 30.570827] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.578034] Dumping ftrace buffer: [ 30.581579] (ftrace buffer empty) [ 30.585276] Kernel Offset: disabled [ 30.588900] Rebooting in 86400 seconds..