[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.178907] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.320696] random: sshd: uninitialized urandom read (32 bytes read) [ 26.756222] random: sshd: uninitialized urandom read (32 bytes read) [ 27.300356] random: sshd: uninitialized urandom read (32 bytes read) [ 27.454748] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.46' (ECDSA) to the list of known hosts. [ 33.056310] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 33.244982] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 33.253313] IP: [] l2tp_session_free+0x11c/0x200 [ 33.260071] PGD 1c2ef8067 [ 33.262713] PUD 1c2f05067 PMD 0 [ 33.266208] [ 33.267823] Oops: 0002 [#1] PREEMPT SMP KASAN [ 33.272408] Dumping ftrace buffer: [ 33.275924] (ftrace buffer empty) [ 33.279610] Modules linked in: [ 33.283001] CPU: 0 PID: 3803 Comm: syz-executor851 Not tainted 4.9.122-g54068d6 #26 [ 33.290791] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.300124] task: ffff8801b767b000 task.stack: ffff8801b58f0000 [ 33.306157] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 33.315101] RSP: 0018:ffff8801b58f7ca0 EFLAGS: 00010246 [ 33.320522] RAX: dffffc0000000000 RBX: ffff8801b5ed3b80 RCX: 0000000000000000 [ 33.327770] RDX: 1ffff10036b1d170 RSI: ffffffff836c39a1 RDI: ffff8801b58e8b80 [ 33.335074] RBP: ffff8801b58f7cc0 R08: ffff8801b767b8e8 R09: 0000000000000000 [ 33.342326] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b58e8a00 [ 33.349675] R13: ffff8801b5ed3b88 R14: 0000000000000000 R15: ffffffff83019be0 [ 33.356921] FS: 0000000000ae4880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 33.365119] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 33.370974] CR2: 0000000000000080 CR3: 00000001c9d10000 CR4: 00000000001606f0 [ 33.378222] Stack: [ 33.380348] ffff8801b5dbe600 ffff8801b5ed3b80 ffff8801b5dbe9d0 ffff8801b5dbe8d8 [ 33.388579] ffff8801b58f7ce8 ffffffff836cb2b2 ffff8801b5dbea40 ffff8801b5dbe600 [ 33.396710] ffffffff836cb1e0 ffff8801b58f7d20 ffffffff830270f5 ffff8801b5dbea40 [ 33.404737] Call Trace: [ 33.407307] [] pppol2tp_session_destruct+0xd2/0x110 [ 33.413960] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 33.420259] [] __sk_destruct+0x55/0x590 [ 33.425865] [] ? sock_release+0x1c0/0x1c0 [ 33.431636] [] sk_destruct+0x63/0x80 [ 33.436975] [] __sk_free+0x4f/0x220 [ 33.442337] [] sk_free+0x2b/0x40 [ 33.447330] [] pppol2tp_release+0x239/0x2e0 [ 33.453276] [] sock_release+0x96/0x1c0 [ 33.458788] [] sock_close+0x16/0x20 [ 33.464040] [] __fput+0x263/0x700 [ 33.469125] [] ____fput+0x15/0x20 [ 33.474204] [] task_work_run+0x10c/0x180 [ 33.479891] [] exit_to_usermode_loop+0xfc/0x120 [ 33.486289] [] do_syscall_64+0x364/0x490 [ 33.491976] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 33.498871] 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 [ 33.525938] RIP [] l2tp_session_free+0x11c/0x200 [ 33.532437] RSP [ 33.536046] CR2: 0000000000000080 [ 33.540161] ---[ end trace a2619e8f32c45001 ]--- [ 33.545093] Kernel panic - not syncing: Fatal exception [ 33.550733] Dumping ftrace buffer: [ 33.554261] (ftrace buffer empty) [ 33.557946] Kernel Offset: disabled [ 33.561545] Rebooting in 86400 seconds..