[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.734697] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.414465] random: sshd: uninitialized urandom read (32 bytes read) [ 17.648974] random: sshd: uninitialized urandom read (32 bytes read) [ 18.552905] random: sshd: uninitialized urandom read (32 bytes read) [ 32.586077] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.37' (ECDSA) to the list of known hosts. [ 37.962558] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 38.184020] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 38.192585] IP: [] l2tp_session_free+0x11c/0x200 [ 38.199046] PGD 1bdc7a067 [ 38.201714] PUD 1bdc7b067 PMD 0 [ 38.205228] [ 38.206859] Oops: 0002 [#1] PREEMPT SMP KASAN [ 38.211333] Dumping ftrace buffer: [ 38.214873] (ftrace buffer empty) [ 38.218560] Modules linked in: [ 38.221847] CPU: 0 PID: 3810 Comm: syz-executor566 Not tainted 4.9.113-g47bbcd6 #10 [ 38.229756] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 38.239094] task: ffff8801b7450000 task.stack: ffff8801d8cd0000 [ 38.245124] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 38.254092] RSP: 0018:ffff8801d8cd7ca0 EFLAGS: 00010246 [ 38.259517] RAX: dffffc0000000000 RBX: ffff8801c8ea2000 RCX: 0000000000000000 [ 38.266778] RDX: 1ffff10036c8be60 RSI: ffffffff836bcce1 RDI: ffff8801b645f300 [ 38.274021] RBP: ffff8801d8cd7cc0 R08: ffff8801b74508e8 R09: 0000000000000000 [ 38.281263] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b645f180 [ 38.288506] R13: ffff8801c8ea2008 R14: 0000000000000000 R15: ffffffff83013be0 [ 38.295766] FS: 0000000002050880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 38.304014] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 38.309882] CR2: 0000000000000080 CR3: 00000001c3b8e000 CR4: 00000000001606f0 [ 38.317228] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 38.324477] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 38.331739] Stack: [ 38.333885] ffff8801d8ebe600 ffff8801c8ea2000 ffff8801d8ebe9d0 ffff8801d8ebe8d8 [ 38.342559] ffff8801d8cd7ce8 ffffffff836c45f2 ffff8801d8ebea40 ffff8801d8ebe600 [ 38.350586] ffffffff836c4520 ffff8801d8cd7d20 ffffffff83021095 ffff8801d8ebea40 [ 38.358602] Call Trace: [ 38.361189] [] pppol2tp_session_destruct+0xd2/0x110 [ 38.367836] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 38.374400] [] __sk_destruct+0x55/0x590 [ 38.380269] [] ? sock_release+0x1c0/0x1c0 [ 38.386050] [] sk_destruct+0x63/0x80 [ 38.391394] [] __sk_free+0x4f/0x220 [ 38.396648] [] sk_free+0x2b/0x40 [ 38.401784] [] pppol2tp_release+0x239/0x2e0 [ 38.407775] [] sock_release+0x96/0x1c0 [ 38.413299] [] sock_close+0x16/0x20 [ 38.418573] [] __fput+0x263/0x700 [ 38.423667] [] ____fput+0x15/0x20 [ 38.428763] [] task_work_run+0x10c/0x180 [ 38.434460] [] exit_to_usermode_loop+0xfc/0x120 [ 38.440941] [] do_syscall_64+0x364/0x490 [ 38.446643] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 38.453682] Code: 49 8d bc 24 80 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c6 00 00 00 4d 8b b4 24 80 01 00 00 41 ff 8e 80 00 00 00 74 69 e8 55 1d ca fd 4c 89 ea 48 b8 00 [ 38.482039] RIP [] l2tp_session_free+0x11c/0x200 [ 38.488902] RSP [ 38.492587] CR2: 0000000000000080 [ 38.496127] ---[ end trace e55e2e4a84db83f8 ]--- [ 38.500892] Kernel panic - not syncing: Fatal exception [ 38.506862] Dumping ftrace buffer: [ 38.510387] (ftrace buffer empty) [ 38.514171] Kernel Offset: disabled [ 38.517814] Rebooting in 86400 seconds..