[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.850915] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.558470] random: sshd: uninitialized urandom read (32 bytes read) [ 17.917918] random: sshd: uninitialized urandom read (32 bytes read) [ 18.410023] random: sshd: uninitialized urandom read (32 bytes read) [ 23.598945] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.56' (ECDSA) to the list of known hosts. [ 29.230941] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 29.438883] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 29.447101] IP: [] l2tp_session_free+0x11c/0x200 [ 29.453528] PGD 1c3e48067 [ 29.456174] PUD 1c3fc2067 PMD 0 [ 29.459663] [ 29.461373] Oops: 0002 [#1] PREEMPT SMP KASAN [ 29.465844] Dumping ftrace buffer: [ 29.469782] (ftrace buffer empty) [ 29.473472] Modules linked in: [ 29.476766] CPU: 0 PID: 3798 Comm: syz-executor356 Not tainted 4.9.120-gf85543b #76 [ 29.484536] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 29.493874] task: ffff8801b68e3000 task.stack: ffff8801da368000 [ 29.500053] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 29.508914] RSP: 0018:ffff8801da36fca0 EFLAGS: 00010246 [ 29.514378] RAX: dffffc0000000000 RBX: ffff8801b6f86780 RCX: 0000000000000000 [ 29.521639] RDX: 1ffff100398df5c0 RSI: ffffffff836c29a1 RDI: ffff8801cc6fae00 [ 29.528909] RBP: ffff8801da36fcc0 R08: ffff8801b68e38e8 R09: 0000000000000000 [ 29.536161] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cc6fac80 [ 29.543414] R13: ffff8801b6f86788 R14: 0000000000000000 R15: ffffffff83018be0 [ 29.550664] FS: 000000000130a880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 29.558872] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 29.564751] CR2: 0000000000000080 CR3: 00000001c9172000 CR4: 00000000001606f0 [ 29.572040] Stack: [ 29.574184] ffff8801b65b1100 ffff8801b6f86780 ffff8801b65b14d0 ffff8801b65b13d8 [ 29.582223] ffff8801da36fce8 ffffffff836ca2b2 ffff8801b65b1540 ffff8801b65b1100 [ 29.590272] ffffffff836ca1e0 ffff8801da36fd20 ffffffff830260f5 ffff8801b65b1540 [ 29.598269] Call Trace: [ 29.600837] [] pppol2tp_session_destruct+0xd2/0x110 [ 29.607490] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 29.613789] [] __sk_destruct+0x55/0x590 [ 29.619410] [] ? sock_release+0x1c0/0x1c0 [ 29.625233] [] sk_destruct+0x63/0x80 [ 29.630629] [] __sk_free+0x4f/0x220 [ 29.635892] [] sk_free+0x2b/0x40 [ 29.640914] [] pppol2tp_release+0x239/0x2e0 [ 29.646867] [] sock_release+0x96/0x1c0 [ 29.652390] [] sock_close+0x16/0x20 [ 29.657659] [] __fput+0x263/0x700 [ 29.662750] [] ____fput+0x15/0x20 [ 29.667839] [] task_work_run+0x10c/0x180 [ 29.673531] [] exit_to_usermode_loop+0xfc/0x120 [ 29.679836] [] do_syscall_64+0x364/0x490 [ 29.685555] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 29.692454] 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 15 de c9 fd 4c 89 ea 48 b8 00 [ 29.719812] RIP [] l2tp_session_free+0x11c/0x200 [ 29.726331] RSP [ 29.729930] CR2: 0000000000000080 [ 29.733669] ---[ end trace d5421b1b5c5a4f02 ]--- [ 29.738456] Kernel panic - not syncing: Fatal exception [ 29.744109] Dumping ftrace buffer: [ 29.747635] (ftrace buffer empty) [ 29.751324] Kernel Offset: disabled [ 29.754928] Rebooting in 86400 seconds..