[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.708609] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.995961] random: sshd: uninitialized urandom read (32 bytes read) [ 17.206602] random: sshd: uninitialized urandom read (32 bytes read) [ 17.696982] random: sshd: uninitialized urandom read (32 bytes read) [ 35.140055] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.36' (ECDSA) to the list of known hosts. [ 40.894061] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 41.100372] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 41.108712] IP: [] l2tp_session_free+0x11c/0x200 [ 41.115145] PGD 1c3136067 [ 41.117792] PUD 1c3168067 PMD 0 [ 41.121342] [ 41.122968] Oops: 0002 [#1] PREEMPT SMP KASAN [ 41.127478] Dumping ftrace buffer: [ 41.130998] (ftrace buffer empty) [ 41.134686] Modules linked in: [ 41.137990] CPU: 1 PID: 3799 Comm: syz-executor024 Not tainted 4.9.122-g54068d6 #78 [ 41.145775] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 41.155130] task: ffff8801ba7a4800 task.stack: ffff8801b9dc8000 [ 41.161161] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 41.170253] RSP: 0018:ffff8801b9dcfca0 EFLAGS: 00010246 [ 41.175687] RAX: dffffc0000000000 RBX: ffff8801b8e6ef00 RCX: 0000000000000000 [ 41.183049] RDX: 1ffff100391d2750 RSI: ffffffff836c39a1 RDI: ffff8801c8e93a80 [ 41.190304] RBP: ffff8801b9dcfcc0 R08: ffff8801ba7a50e8 R09: 0000000000000000 [ 41.197560] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c8e93900 [ 41.204812] R13: ffff8801b8e6ef08 R14: 0000000000000000 R15: ffffffff83019be0 [ 41.212213] FS: 0000000001d6e880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 41.220439] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 41.226312] CR2: 0000000000000080 CR3: 00000001c7ce9000 CR4: 00000000001606f0 [ 41.233635] Stack: [ 41.235818] ffff8801d95a1980 ffff8801b8e6ef00 ffff8801d95a1d50 ffff8801d95a1c58 [ 41.243956] ffff8801b9dcfce8 ffffffff836cb2b2 ffff8801d95a1dc0 ffff8801d95a1980 [ 41.251978] ffffffff836cb1e0 ffff8801b9dcfd20 ffffffff830270f5 ffff8801d95a1dc0 [ 41.260047] Call Trace: [ 41.262685] [] pppol2tp_session_destruct+0xd2/0x110 [ 41.269361] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 41.275699] [] __sk_destruct+0x55/0x590 [ 41.281306] [] ? sock_release+0x1c0/0x1c0 [ 41.287083] [] sk_destruct+0x63/0x80 [ 41.292424] [] __sk_free+0x4f/0x220 [ 41.297684] [] sk_free+0x2b/0x40 [ 41.302704] [] pppol2tp_release+0x239/0x2e0 [ 41.308740] [] sock_release+0x96/0x1c0 [ 41.314262] [] sock_close+0x16/0x20 [ 41.319522] [] __fput+0x263/0x700 [ 41.324726] [] ____fput+0x15/0x20 [ 41.329812] [] task_work_run+0x10c/0x180 [ 41.335506] [] exit_to_usermode_loop+0xfc/0x120 [ 41.341805] [] do_syscall_64+0x364/0x490 [ 41.347516] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 41.354426] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 41.381821] RIP [] l2tp_session_free+0x11c/0x200 [ 41.388331] RSP [ 41.391962] CR2: 0000000000000080 [ 41.395533] ---[ end trace 89617386496d0530 ]--- [ 41.400395] Kernel panic - not syncing: Fatal exception [ 41.406061] Dumping ftrace buffer: [ 41.409586] (ftrace buffer empty) [ 41.413274] Kernel Offset: disabled [ 41.416877] Rebooting in 86400 seconds..