[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.537559] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 14.272273] random: sshd: uninitialized urandom read (32 bytes read) [ 14.553903] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.077299] random: sshd: uninitialized urandom read (32 bytes read) [ 15.220069] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.46' (ECDSA) to the list of known hosts. [ 21.017962] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.213657] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.221950] IP: [] l2tp_session_free+0x11c/0x200 [ 21.228399] PGD 1cb293067 [ 21.231042] PUD 1cb0b2067 PMD 0 [ 21.234540] [ 21.236166] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.240639] Dumping ftrace buffer: [ 21.244155] (ftrace buffer empty) [ 21.247854] Modules linked in: [ 21.251145] CPU: 1 PID: 3795 Comm: syz-executor232 Not tainted 4.9.122-g54068d6 #26 [ 21.258915] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.268247] task: ffff8801b6c6b000 task.stack: ffff8801b7850000 [ 21.274276] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.283131] RSP: 0018:ffff8801b7857ca0 EFLAGS: 00010246 [ 21.288554] RAX: dffffc0000000000 RBX: ffff8801b719ac80 RCX: 0000000000000000 [ 21.295802] RDX: 1ffff10036e0d480 RSI: ffffffff836c39a1 RDI: ffff8801b706a400 [ 21.303078] RBP: ffff8801b7857cc0 R08: ffff8801b6c6b8e8 R09: 0000000000000000 [ 21.310324] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b706a280 [ 21.317568] R13: ffff8801b719ac88 R14: 0000000000000000 R15: ffffffff83019be0 [ 21.324824] FS: 0000000000a4a880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 21.333023] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.338877] CR2: 0000000000000080 CR3: 00000001bebc3000 CR4: 00000000001606f0 [ 21.346124] Stack: [ 21.348251] ffff8801b5f3aa80 ffff8801b719ac80 ffff8801b5f3ae50 ffff8801b5f3ad58 [ 21.356250] ffff8801b7857ce8 ffffffff836cb2b2 ffff8801b5f3aec0 ffff8801b5f3aa80 [ 21.364256] ffffffff836cb1e0 ffff8801b7857d20 ffffffff830270f5 ffff8801b5f3aec0 [ 21.372252] Call Trace: [ 21.374820] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.381464] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.387782] [] __sk_destruct+0x55/0x590 [ 21.393393] [] ? sock_release+0x1c0/0x1c0 [ 21.399169] [] sk_destruct+0x63/0x80 [ 21.404511] [] __sk_free+0x4f/0x220 [ 21.409766] [] sk_free+0x2b/0x40 [ 21.414757] [] pppol2tp_release+0x239/0x2e0 [ 21.420709] [] sock_release+0x96/0x1c0 [ 21.426221] [] sock_close+0x16/0x20 [ 21.431477] [] __fput+0x263/0x700 [ 21.436559] [] ____fput+0x15/0x20 [ 21.441649] [] task_work_run+0x10c/0x180 [ 21.447337] [] exit_to_usermode_loop+0xfc/0x120 [ 21.453630] [] do_syscall_64+0x364/0x490 [ 21.459317] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.466221] 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 [ 21.493205] RIP [] l2tp_session_free+0x11c/0x200 [ 21.499713] RSP [ 21.503315] CR2: 0000000000000080 [ 21.506859] ---[ end trace 44d4d0991888a395 ]--- [ 21.511614] Kernel panic - not syncing: Fatal exception [ 21.517262] Dumping ftrace buffer: [ 21.520788] (ftrace buffer empty) [ 21.524472] Kernel Offset: disabled [ 21.528070] Rebooting in 86400 seconds..