[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.450134] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.776400] random: sshd: uninitialized urandom read (32 bytes read) [ 19.272599] random: sshd: uninitialized urandom read (32 bytes read) [ 19.772124] random: sshd: uninitialized urandom read (32 bytes read) [ 19.908048] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.21' (ECDSA) to the list of known hosts. [ 25.373150] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.581333] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.589544] IP: [] l2tp_session_free+0x11c/0x200 [ 25.595959] PGD 1ca0eb067 [ 25.598600] PUD 1c4cf6067 PMD 0 [ 25.602074] [ 25.603694] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.608158] Dumping ftrace buffer: [ 25.611672] (ftrace buffer empty) [ 25.615352] Modules linked in: [ 25.618637] CPU: 0 PID: 3652 Comm: syz-executor537 Not tainted 4.9.117-g8b21e85 #19 [ 25.626402] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.635729] task: ffff8801c4a20000 task.stack: ffff8801c4c80000 [ 25.641754] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.650606] RSP: 0018:ffff8801c4c87ca0 EFLAGS: 00010246 [ 25.656026] RAX: dffffc0000000000 RBX: ffff8801c4762f00 RCX: 0000000000000000 [ 25.663267] RDX: 1ffff100388cf080 RSI: ffffffff836bf8f1 RDI: ffff8801c4678400 [ 25.670508] RBP: ffff8801c4c87cc0 R08: ffff8801c4a208e8 R09: 0000000000000000 [ 25.677764] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c4678280 [ 25.685007] R13: ffff8801c4762f08 R14: 0000000000000000 R15: ffffffff83015be0 [ 25.692246] FS: 000000000187a880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 25.700441] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.706292] CR2: 0000000000000080 CR3: 00000001c8447000 CR4: 00000000001606f0 [ 25.713532] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.720783] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.728031] Stack: [ 25.730149] ffff8801c43bbb80 ffff8801c4762f00 ffff8801c43bbf50 ffff8801c43bbe58 [ 25.738126] ffff8801c4c87ce8 ffffffff836c7202 ffff8801c43bbfc0 ffff8801c43bbb80 [ 25.746104] ffffffff836c7130 ffff8801c4c87d20 ffffffff83023095 ffff8801c43bbfc0 [ 25.754094] Call Trace: [ 25.756664] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.763313] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.769614] [] __sk_destruct+0x55/0x590 [ 25.775212] [] ? sock_release+0x1c0/0x1c0 [ 25.780980] [] sk_destruct+0x63/0x80 [ 25.786324] [] __sk_free+0x4f/0x220 [ 25.791571] [] sk_free+0x2b/0x40 [ 25.796557] [] pppol2tp_release+0x239/0x2e0 [ 25.802500] [] sock_release+0x96/0x1c0 [ 25.808008] [] sock_close+0x16/0x20 [ 25.813255] [] __fput+0x263/0x700 [ 25.818330] [] ____fput+0x15/0x20 [ 25.823406] [] task_work_run+0x10c/0x180 [ 25.829087] [] exit_to_usermode_loop+0xfc/0x120 [ 25.835387] [] do_syscall_64+0x364/0x490 [ 25.841072] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.847976] 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 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 25.874785] RIP [] l2tp_session_free+0x11c/0x200 [ 25.881285] RSP [ 25.884898] CR2: 0000000000000080 [ 25.888494] ---[ end trace b9350920b3db32ed ]--- [ 25.893243] Kernel panic - not syncing: Fatal exception [ 25.898880] Dumping ftrace buffer: [ 25.902392] (ftrace buffer empty) [ 25.906075] Kernel Offset: disabled [ 25.909673] Rebooting in 86400 seconds..