[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.116176] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.866126] random: sshd: uninitialized urandom read (32 bytes read) [ 19.246996] random: sshd: uninitialized urandom read (32 bytes read) [ 20.183026] random: sshd: uninitialized urandom read (32 bytes read) [ 45.385576] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.39' (ECDSA) to the list of known hosts. [ 50.866001] random: sshd: uninitialized urandom read (32 bytes read) 2018/07/13 04:00:40 parsed 1 programs [ 52.282730] random: cc1: uninitialized urandom read (8 bytes read) 2018/07/13 04:00:42 executed programs: 0 [ 53.741539] IPVS: Creating netns size=2536 id=1 [ 53.871745] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 53.884163] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 53.931003] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 53.942908] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 53.987466] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 53.999652] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 54.012833] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 54.034130] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 54.571359] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 54.600120] IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready [ 54.606448] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready [ 54.613204] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 54.897691] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 54.996841] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 55.096637] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 55.206807] l2tp_core: tunl 3: sockfd_lookup(fd=8) returned -9 [ 55.316433] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 55.436027] l2tp_core: tunl 3: sockfd_lookup(fd=8) returned -9 [ 55.606121] ================================================================== [ 55.613520] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 55.620777] Read of size 4 at addr ffff8801d761ef00 by task syz-executor0/4228 [ 55.628118] [ 55.629766] CPU: 1 PID: 4228 Comm: syz-executor0 Not tainted 4.9.112-g9e79039 #11 [ 55.637380] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 55.646724] ffff8801d4107ca0 ffffffff81eb3249 ffffea00075d8780 ffff8801d761ef00 [ 55.654742] 0000000000000000 ffff8801d761ef00 ffffffff83013be0 ffff8801d4107cd8 [ 55.662732] ffffffff81567bd9 ffff8801d761ef00 0000000000000004 0000000000000000 [ 55.670718] Call Trace: [ 55.673286] [<ffffffff81eb3249>] dump_stack+0xc1/0x128 [ 55.678632] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 55.684417] [<ffffffff81567bd9>] print_address_description+0x6c/0x234 [ 55.691068] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 55.696860] [<ffffffff81567fe3>] kasan_report.cold.6+0x242/0x2fe [ 55.703080] [<ffffffff836bbc14>] ? l2tp_session_queue_purge+0xf4/0x100 [ 55.709826] [<ffffffff8153bc14>] __asan_report_load4_noabort+0x14/0x20 [ 55.716568] [<ffffffff836bbc14>] l2tp_session_queue_purge+0xf4/0x100 [ 55.723136] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 55.728925] [<ffffffff836c789b>] pppol2tp_release+0x1fb/0x2e0 [ 55.734891] [<ffffffff83013ab6>] sock_release+0x96/0x1c0 [ 55.740416] [<ffffffff83013bf6>] sock_close+0x16/0x20 [ 55.745674] [<ffffffff815782e3>] __fput+0x263/0x700 [ 55.750763] [<ffffffff81578805>] ____fput+0x15/0x20 [ 55.755858] [<ffffffff8119839c>] task_work_run+0x10c/0x180 [ 55.761549] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 55.767852] [<ffffffff81007073>] do_fast_syscall_32+0x5c3/0x870 [ 55.773980] [<ffffffff81003036>] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 55.780660] [<ffffffff839fb650>] entry_SYSENTER_compat+0x90/0xa2 [ 55.786968] [ 55.788576] Allocated by task 4230: [ 55.792225] save_stack_trace+0x16/0x20 [ 55.796187] save_stack+0x43/0xd0 [ 55.799611] kasan_kmalloc+0xc7/0xe0 [ 55.803300] __kmalloc+0x11d/0x300 [ 55.806823] l2tp_session_create+0x38/0x16f0 [ 55.811209] pppol2tp_connect+0x10d7/0x18f0 [ 55.815504] SYSC_connect+0x1b8/0x300 [ 55.819281] SyS_connect+0x24/0x30 [ 55.822800] do_fast_syscall_32+0x2f7/0x870 [ 55.827440] entry_SYSENTER_compat+0x90/0xa2 [ 55.831817] [ 55.833417] Freed by task 4231: [ 55.836676] save_stack_trace+0x16/0x20 [ 55.840633] save_stack+0x43/0xd0 [ 55.844080] kasan_slab_free+0x72/0xc0 [ 55.847946] kfree+0xfb/0x310 [ 55.851031] l2tp_session_free+0x166/0x200 [ 55.855245] l2tp_tunnel_closeall+0x284/0x350 [ 55.859744] l2tp_udp_encap_destroy+0x87/0xe0 [ 55.864222] udp_destroy_sock+0x118/0x1a0 [ 55.868357] sk_common_release+0x6d/0x300 [ 55.872484] udp_lib_close+0x15/0x20 [ 55.876181] inet_release+0xff/0x1d0 [ 55.879891] sock_release+0x96/0x1c0 [ 55.883596] sock_close+0x16/0x20 [ 55.887037] __fput+0x263/0x700 [ 55.890291] ____fput+0x15/0x20 [ 55.893549] task_work_run+0x10c/0x180 [ 55.897421] exit_to_usermode_loop+0xfc/0x120 [ 55.901917] do_fast_syscall_32+0x5c3/0x870 [ 55.906224] entry_SYSENTER_compat+0x90/0xa2 [ 55.910609] [ 55.912237] The buggy address belongs to the object at ffff8801d761ef00 [ 55.912237] which belongs to the cache kmalloc-512 of size 512 [ 55.924885] The buggy address is located 0 bytes inside of [ 55.924885] 512-byte region [ffff8801d761ef00, ffff8801d761f100) [ 55.936562] The buggy address belongs to the page: [ 55.941480] page:ffffea00075d8780 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 55.951761] flags: 0x8000000000004080(slab|head) [ 55.956520] page dumped because: kasan: bad access detected [ 55.962217] [ 55.963828] Memory state around the buggy address: [ 55.968740] ffff8801d761ee00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 55.976088] ffff8801d761ee80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 55.983446] >ffff8801d761ef00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 55.990791] ^ [ 55.994166] ffff8801d761ef80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 56.001530] ffff8801d761f000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 56.008891] ================================================================== [ 56.016238] Disabling lock debugging due to kernel taint [ 56.022608] Kernel panic - not syncing: panic_on_warn set ... [ 56.022608] [ 56.030073] CPU: 1 PID: 4228 Comm: syz-executor0 Tainted: G B 4.9.112-g9e79039 #11 [ 56.038918] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 56.048264] ffff8801d4107c00 ffffffff81eb3249 ffffffff843c775f 00000000ffffffff [ 56.056308] 0000000000000000 0000000000000001 ffffffff83013be0 ffff8801d4107cc0 [ 56.064313] ffffffff81421a55 0000000041b58ab3 ffffffff843bae78 ffffffff81421896 [ 56.072312] Call Trace: [ 56.074877] [<ffffffff81eb3249>] dump_stack+0xc1/0x128 [ 56.080225] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 56.086009] [<ffffffff81421a55>] panic+0x1bf/0x3bc [ 56.091010] [<ffffffff81421896>] ? add_taint.cold.6+0x16/0x16 [ 56.096997] [<ffffffff81003066>] ? ___preempt_schedule+0x16/0x18 [ 56.103213] [<ffffffff81567af6>] kasan_end_report+0x47/0x4f [ 56.109091] [<ffffffff81567e17>] kasan_report.cold.6+0x76/0x2fe [ 56.115227] [<ffffffff836bbc14>] ? l2tp_session_queue_purge+0xf4/0x100 [ 56.121979] [<ffffffff8153bc14>] __asan_report_load4_noabort+0x14/0x20 [ 56.128726] [<ffffffff836bbc14>] l2tp_session_queue_purge+0xf4/0x100 [ 56.135300] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 56.141087] [<ffffffff836c789b>] pppol2tp_release+0x1fb/0x2e0 [ 56.147048] [<ffffffff83013ab6>] sock_release+0x96/0x1c0 [ 56.152575] [<ffffffff83013bf6>] sock_close+0x16/0x20 [ 56.157840] [<ffffffff815782e3>] __fput+0x263/0x700 [ 56.162937] [<ffffffff81578805>] ____fput+0x15/0x20 [ 56.168038] [<ffffffff8119839c>] task_work_run+0x10c/0x180 [ 56.173737] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 56.180040] [<ffffffff81007073>] do_fast_syscall_32+0x5c3/0x870 [ 56.186176] [<ffffffff81003036>] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 56.192832] [<ffffffff839fb650>] entry_SYSENTER_compat+0x90/0xa2 [ 56.199640] Dumping ftrace buffer: [ 56.203159] (ftrace buffer empty) [ 56.206854] Kernel Offset: disabled [ 56.210465] Rebooting in 86400 seconds..