[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.483245] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 13.611304] random: sshd: uninitialized urandom read (32 bytes read) [ 13.804023] random: sshd: uninitialized urandom read (32 bytes read) [ 14.604751] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 29.019966] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.58' (ECDSA) to the list of known hosts. [ 34.742032] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.964501] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.972877] IP: [] l2tp_session_free+0x11c/0x200 [ 34.979334] PGD 1c3e4a067 [ 34.981978] PUD 1c726a067 PMD 0 [ 34.985467] [ 34.987088] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.991554] Dumping ftrace buffer: [ 34.995064] (ftrace buffer empty) [ 34.998750] Modules linked in: [ 35.002045] CPU: 0 PID: 3809 Comm: syz-executor209 Not tainted 4.9.124-g09eb2ba #31 [ 35.009812] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 35.019139] task: ffff8801b7113000 task.stack: ffff8801d9120000 [ 35.025168] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 35.034019] RSP: 0018:ffff8801d9127c98 EFLAGS: 00010246 [ 35.039440] RAX: dffffc0000000000 RBX: ffff8801ca72aa00 RCX: 0000000000000000 [ 35.046708] RDX: 1ffff10036f0fab0 RSI: ffffffff836c4711 RDI: ffff8801b787d580 [ 35.054494] RBP: ffff8801d9127cb8 R08: ffff8801b71138e8 R09: 0000000000000000 [ 35.061747] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b787d400 [ 35.068989] R13: ffff8801ca72aa08 R14: 0000000000000000 R15: 0000000000000000 [ 35.076236] FS: 0000000001a3e880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 35.084435] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 35.090304] CR2: 0000000000000080 CR3: 00000001c3d78000 CR4: 00000000001606f0 [ 35.097549] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 35.104794] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 35.112044] Stack: [ 35.114165] ffff8801b73ec400 ffff8801ca72aa00 ffff8801b73ec7d0 ffff8801b73ec6d8 [ 35.122154] ffff8801d9127ce0 ffffffff836cc022 ffff8801b73ec840 ffff8801b73ec400 [ 35.130169] ffffffff836cbf50 ffff8801d9127d18 ffffffff830281f5 ffff8801b73ec840 [ 35.138157] Call Trace: [ 35.140728] [] pppol2tp_session_destruct+0xd2/0x110 [ 35.147378] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 35.153683] [] __sk_destruct+0x55/0x590 [ 35.159292] [] sk_destruct+0x63/0x80 [ 35.164632] [] __sk_free+0x4f/0x220 [ 35.169884] [] sk_free+0x2b/0x40 [ 35.174882] [] pppol2tp_release+0x239/0x2e0 [ 35.180829] [] __sock_release+0xd7/0x260 [ 35.186517] [] ? __sock_release+0x260/0x260 [ 35.192463] [] sock_close+0x19/0x20 [ 35.197732] [] __fput+0x263/0x700 [ 35.202811] [] ____fput+0x15/0x20 [ 35.207890] [] task_work_run+0x10c/0x180 [ 35.213576] [] exit_to_usermode_loop+0xfc/0x120 [ 35.219873] [] do_syscall_64+0x364/0x490 [ 35.225560] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 35.232489] 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 a5 c5 c9 fd 4c 89 ea 48 b8 00 [ 35.259357] RIP [] l2tp_session_free+0x11c/0x200 [ 35.265869] RSP [ 35.269464] CR2: 0000000000000080 [ 35.272973] ---[ end trace 3c86af130c13b65d ]--- [ 35.277757] Kernel panic - not syncing: Fatal exception [ 35.283437] Dumping ftrace buffer: [ 35.286955] (ftrace buffer empty) [ 35.290638] Kernel Offset: disabled [ 35.294235] Rebooting in 86400 seconds..