[....] Starting OpenBSD Secure Shell server: sshd[ 14.645105] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 14.906974] random: sshd: uninitialized urandom read (32 bytes read) [ 15.156733] random: sshd: uninitialized urandom read (32 bytes read) [ 15.680888] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 [ 15.816280] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.195' (ECDSA) to the list of known hosts. syzkaller login: [ 21.427405] random: sshd: uninitialized urandom read (32 bytes read) 2018/08/22 23:55:34 parsed 1 programs [ 22.460111] random: cc1: uninitialized urandom read (8 bytes read) 2018/08/22 23:55:36 executed programs: 0 [ 24.060239] IPVS: Creating netns size=2536 id=1 [ 24.181843] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 24.193403] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 24.235358] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 24.246792] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 24.292294] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 24.303951] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 24.315524] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 24.329142] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 24.853607] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 24.879074] IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready [ 24.885156] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready [ 24.892604] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 25.131849] hrtimer: interrupt took 19610 ns [ 25.431504] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 25.563427] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 25.604832] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 25.645167] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 25.742819] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 25.756659] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 25.809268] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 25.856832] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 25.947965] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 25.980050] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.069537] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.114579] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.130500] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.143703] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.204023] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.241295] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.286668] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.303448] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.343076] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.395004] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.470688] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.519964] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.533310] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.657362] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.726769] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.741364] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.768224] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.789931] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.804982] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.862209] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 26.965297] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 27.002240] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 27.074704] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 27.110236] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 27.158143] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 27.203884] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 27.280538] ================================================================== [ 27.287932] BUG: KASAN: use-after-free in pppol2tp_session_destruct+0xed/0x110 [ 27.295278] Read of size 4 at addr ffff8801c2a12a00 by task syz-executor0/5103 [ 27.302607] [ 27.304212] CPU: 1 PID: 5103 Comm: syz-executor0 Not tainted 4.9.123-g8dd3fc2 #79 [ 27.311803] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.321137] ffff8801c1bafc30 ffffffff81eb9689 ffffea00070a8480 ffff8801c2a12a00 [ 27.329166] 0000000000000000 ffff8801c2a12a00 ffffffff8301abe0 ffff8801c1bafc68 [ 27.337201] ffffffff8156c3fe ffff8801c2a12a00 0000000000000004 0000000000000000 [ 27.345255] Call Trace: [ 27.347822] [] dump_stack+0xc1/0x128 [ 27.353164] [] ? sock_release+0x1c0/0x1c0 [ 27.358940] [] print_address_description+0x6c/0x234 [ 27.365582] [] ? sock_release+0x1c0/0x1c0 [ 27.371370] [] kasan_report.cold.6+0x242/0x2fe [ 27.377579] [] ? pppol2tp_session_destruct+0xed/0x110 [ 27.384396] [] __asan_report_load4_noabort+0x14/0x20 [ 27.391133] [] pppol2tp_session_destruct+0xed/0x110 [ 27.397791] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.404101] [] __sk_destruct+0x55/0x590 [ 27.409707] [] ? sock_release+0x1c0/0x1c0 [ 27.415481] [] sk_destruct+0x63/0x80 [ 27.420819] [] __sk_free+0x4f/0x220 [ 27.426069] [] sk_free+0x2b/0x40 [ 27.431079] [] pppol2tp_release+0x239/0x2e0 [ 27.437037] [] sock_release+0x96/0x1c0 [ 27.442553] [] sock_close+0x16/0x20 [ 27.447806] [] __fput+0x263/0x700 [ 27.452886] [] ____fput+0x15/0x20 [ 27.457974] [] task_work_run+0x10c/0x180 [ 27.463666] [] exit_to_usermode_loop+0xfc/0x120 [ 27.469962] [] do_syscall_64+0x364/0x490 [ 27.475650] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.482545] [ 27.484154] Allocated by task 5104: [ 27.487755] save_stack_trace+0x16/0x20 [ 27.491708] save_stack+0x43/0xd0 [ 27.495181] kasan_kmalloc+0xc7/0xe0 [ 27.498877] __kmalloc+0x11d/0x300 [ 27.502399] l2tp_session_create+0x38/0x16f0 [ 27.506818] pppol2tp_connect+0x10d7/0x18f0 [ 27.511126] SYSC_connect+0x1b8/0x300 [ 27.514922] SyS_connect+0x24/0x30 [ 27.518446] do_syscall_64+0x1a6/0x490 [ 27.522326] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.527450] [ 27.529057] Freed by task 5104: [ 27.532549] save_stack_trace+0x16/0x20 [ 27.536499] save_stack+0x43/0xd0 [ 27.539930] kasan_slab_free+0x72/0xc0 [ 27.543798] kfree+0xfb/0x310 [ 27.546880] l2tp_session_free+0x166/0x200 [ 27.551111] l2tp_tunnel_closeall+0x284/0x350 [ 27.555585] l2tp_udp_encap_destroy+0x87/0xe0 [ 27.560057] udpv6_destroy_sock+0xb1/0xd0 [ 27.564182] sk_common_release+0x6d/0x300 [ 27.568312] udp_lib_close+0x15/0x20 [ 27.572022] inet_release+0xff/0x1d0 [ 27.575712] inet6_release+0x50/0x70 [ 27.579403] sock_release+0x96/0x1c0 [ 27.583095] sock_close+0x16/0x20 [ 27.586540] __fput+0x263/0x700 [ 27.589803] ____fput+0x15/0x20 [ 27.593071] task_work_run+0x10c/0x180 [ 27.596936] exit_to_usermode_loop+0xfc/0x120 [ 27.601407] do_syscall_64+0x364/0x490 [ 27.605274] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.610351] [ 27.611954] The buggy address belongs to the object at ffff8801c2a12a00 [ 27.611954] which belongs to the cache kmalloc-512 of size 512 [ 27.624585] The buggy address is located 0 bytes inside of [ 27.624585] 512-byte region [ffff8801c2a12a00, ffff8801c2a12c00) [ 27.636255] The buggy address belongs to the page: [ 27.641163] page:ffffea00070a8480 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 27.651353] flags: 0x8000000000004080(slab|head) [ 27.656081] page dumped because: kasan: bad access detected [ 27.661763] [ 27.663362] Memory state around the buggy address: [ 27.668266] ffff8801c2a12900: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc [ 27.675598] ffff8801c2a12980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 27.682931] >ffff8801c2a12a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 27.690263] ^ [ 27.693603] ffff8801c2a12a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 27.701047] ffff8801c2a12b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 27.708393] ================================================================== [ 27.715736] Disabling lock debugging due to kernel taint [ 27.721288] Kernel panic - not syncing: panic_on_warn set ... [ 27.721288] [ 27.728662] CPU: 1 PID: 5103 Comm: syz-executor0 Tainted: G B 4.9.123-g8dd3fc2 #79 [ 27.737482] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.746812] ffff8801c1bafb90 ffffffff81eb9689 ffffffff843c821b 00000000ffffffff [ 27.754818] 0000000000000000 0000000000000001 ffffffff8301abe0 ffff8801c1bafc50 [ 27.762841] ffffffff81423f75 0000000041b58ab3 ffffffff843bb878 ffffffff81423db6 [ 27.770847] Call Trace: [ 27.773437] [] dump_stack+0xc1/0x128 [ 27.778787] [] ? sock_release+0x1c0/0x1c0 [ 27.784560] [] panic+0x1bf/0x3bc [ 27.789551] [] ? add_taint.cold.6+0x16/0x16 [ 27.795498] [] ? ___preempt_schedule+0x16/0x18 [ 27.801798] [] kasan_end_report+0x47/0x4f [ 27.807584] [] kasan_report.cold.6+0x76/0x2fe [ 27.813706] [] ? pppol2tp_session_destruct+0xed/0x110 [ 27.820525] [] __asan_report_load4_noabort+0x14/0x20 [ 27.827258] [] pppol2tp_session_destruct+0xed/0x110 [ 27.833907] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.840218] [] __sk_destruct+0x55/0x590 [ 27.845844] [] ? sock_release+0x1c0/0x1c0 [ 27.851615] [] sk_destruct+0x63/0x80 [ 27.856953] [] __sk_free+0x4f/0x220 [ 27.862205] [] sk_free+0x2b/0x40 [ 27.867204] [] pppol2tp_release+0x239/0x2e0 [ 27.873155] [] sock_release+0x96/0x1c0 [ 27.878667] [] sock_close+0x16/0x20 [ 27.883926] [] __fput+0x263/0x700 [ 27.889012] [] ____fput+0x15/0x20 [ 27.894093] [] task_work_run+0x10c/0x180 [ 27.899779] [] exit_to_usermode_loop+0xfc/0x120 [ 27.906074] [] do_syscall_64+0x364/0x490 [ 27.911760] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.919070] Dumping ftrace buffer: [ 27.922592] (ftrace buffer empty) [ 27.926277] Kernel Offset: disabled [ 27.929875] Rebooting in 86400 seconds..