[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.777013] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.129596] random: sshd: uninitialized urandom read (32 bytes read) [ 27.617669] random: sshd: uninitialized urandom read (32 bytes read) [ 28.129296] random: sshd: uninitialized urandom read (32 bytes read) [ 28.269588] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.39' (ECDSA) to the list of known hosts. [ 33.771989] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 33.971215] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 33.979470] IP: [] l2tp_session_free+0x11c/0x200 [ 33.985887] PGD 1c2eb6067 [ 33.988629] PUD 1c2e28067 PMD 0 [ 33.992119] [ 33.993741] Oops: 0002 [#1] PREEMPT SMP KASAN [ 33.998211] Dumping ftrace buffer: [ 34.001724] (ftrace buffer empty) [ 34.005410] Modules linked in: [ 34.008693] CPU: 0 PID: 3790 Comm: syz-executor182 Not tainted 4.9.121-g681e57b #77 [ 34.016458] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.025793] task: ffff8801ba36b000 task.stack: ffff8801cae90000 [ 34.031821] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.040676] RSP: 0018:ffff8801cae97ca0 EFLAGS: 00010246 [ 34.046112] RAX: dffffc0000000000 RBX: ffff8801ba45ac80 RCX: 0000000000000000 [ 34.053370] RDX: 1ffff10038e94ba0 RSI: ffffffff836c29a1 RDI: ffff8801c74a5d00 [ 34.060615] RBP: ffff8801cae97cc0 R08: ffff8801ba36b8e8 R09: 0000000000000000 [ 34.067866] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c74a5b80 [ 34.075117] R13: ffff8801ba45ac88 R14: 0000000000000000 R15: ffffffff83018be0 [ 34.082370] FS: 0000000000c61880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 34.090568] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.096423] CR2: 0000000000000080 CR3: 00000001c2c0b000 CR4: 00000000001606f0 [ 34.103669] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 34.110920] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 34.118162] Stack: [ 34.120284] ffff8801bb4f3b80 ffff8801ba45ac80 ffff8801bb4f3f50 ffff8801bb4f3e58 [ 34.128278] ffff8801cae97ce8 ffffffff836ca2b2 ffff8801bb4f3fc0 ffff8801bb4f3b80 [ 34.136268] ffffffff836ca1e0 ffff8801cae97d20 ffffffff830260f5 ffff8801bb4f3fc0 [ 34.144271] Call Trace: [ 34.146839] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.153478] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.159778] [] __sk_destruct+0x55/0x590 [ 34.165379] [] ? sock_release+0x1c0/0x1c0 [ 34.171153] [] sk_destruct+0x63/0x80 [ 34.176594] [] __sk_free+0x4f/0x220 [ 34.181912] [] sk_free+0x2b/0x40 [ 34.186915] [] pppol2tp_release+0x239/0x2e0 [ 34.192866] [] sock_release+0x96/0x1c0 [ 34.198381] [] sock_close+0x16/0x20 [ 34.203636] [] __fput+0x263/0x700 [ 34.208719] [] ____fput+0x15/0x20 [ 34.213804] [] task_work_run+0x10c/0x180 [ 34.219500] [] exit_to_usermode_loop+0xfc/0x120 [ 34.225807] [] do_syscall_64+0x364/0x490 [ 34.231510] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.238408] 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 65 df c9 fd 4c 89 ea 48 b8 00 [ 34.265465] RIP [] l2tp_session_free+0x11c/0x200 [ 34.271975] RSP [ 34.275578] CR2: 0000000000000080 [ 34.279311] ---[ end trace 8c6b1ddbdf9a7db1 ]--- [ 34.284073] Kernel panic - not syncing: Fatal exception [ 34.289778] Dumping ftrace buffer: [ 34.293298] (ftrace buffer empty) [ 34.296981] Kernel Offset: disabled [ 34.300580] Rebooting in 86400 seconds..