[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 17.262431] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.374958] random: sshd: uninitialized urandom read (32 bytes read) [ 26.897633] random: sshd: uninitialized urandom read (32 bytes read) [ 27.390298] random: sshd: uninitialized urandom read (32 bytes read) [ 27.533828] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.46' (ECDSA) to the list of known hosts. [ 33.185079] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 33.406053] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 33.414412] IP: [] l2tp_session_free+0x11c/0x200 [ 33.420831] PGD 1b89c8067 [ 33.423473] PUD 1c6468067 PMD 0 [ 33.426952] [ 33.428578] Oops: 0002 [#1] PREEMPT SMP KASAN [ 33.433049] Dumping ftrace buffer: [ 33.436560] (ftrace buffer empty) [ 33.440251] Modules linked in: [ 33.443645] CPU: 0 PID: 3806 Comm: syz-executor049 Not tainted 4.9.120-gf85543b #24 [ 33.451420] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.460752] task: ffff8801b6f76000 task.stack: ffff8801b5f60000 [ 33.466787] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 33.475643] RSP: 0018:ffff8801b5f67ca0 EFLAGS: 00010246 [ 33.481070] RAX: dffffc0000000000 RBX: ffff8801b5d44280 RCX: 0000000000000000 [ 33.488318] RDX: 1ffff10036ba8970 RSI: ffffffff836c29a1 RDI: ffff8801b5d44b80 [ 33.495569] RBP: ffff8801b5f67cc0 R08: ffff8801b6f768e8 R09: 0000000000000000 [ 33.502860] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5d44a00 [ 33.510115] R13: ffff8801b5d44288 R14: 0000000000000000 R15: ffffffff83018be0 [ 33.517367] FS: 0000000001a04880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 33.525569] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 33.531438] CR2: 0000000000000080 CR3: 00000001c285e000 CR4: 00000000001606f0 [ 33.538701] Stack: [ 33.540833] ffff8801b5fea200 ffff8801b5d44280 ffff8801b5fea5d0 ffff8801b5fea4d8 [ 33.548900] ffff8801b5f67ce8 ffffffff836ca2b2 ffff8801b5fea640 ffff8801b5fea200 [ 33.556898] ffffffff836ca1e0 ffff8801b5f67d20 ffffffff830260f5 ffff8801b5fea640 [ 33.564887] Call Trace: [ 33.567508] [] pppol2tp_session_destruct+0xd2/0x110 [ 33.574169] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 33.580467] [] __sk_destruct+0x55/0x590 [ 33.586184] [] ? sock_release+0x1c0/0x1c0 [ 33.592033] [] sk_destruct+0x63/0x80 [ 33.597388] [] __sk_free+0x4f/0x220 [ 33.602650] [] sk_free+0x2b/0x40 [ 33.607652] [] pppol2tp_release+0x239/0x2e0 [ 33.613609] [] sock_release+0x96/0x1c0 [ 33.619127] [] sock_close+0x16/0x20 [ 33.624389] [] __fput+0x263/0x700 [ 33.629472] [] ____fput+0x15/0x20 [ 33.634553] [] task_work_run+0x10c/0x180 [ 33.640245] [] exit_to_usermode_loop+0xfc/0x120 [ 33.646545] [] do_syscall_64+0x364/0x490 [ 33.652248] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 33.659156] 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 15 de c9 fd 4c 89 ea 48 b8 00 [ 33.686343] RIP [] l2tp_session_free+0x11c/0x200 [ 33.692898] RSP [ 33.696551] CR2: 0000000000000080 [ 33.701168] ---[ end trace cd132b42c05b1fc1 ]--- [ 33.705955] Kernel panic - not syncing: Fatal exception [ 33.711602] Dumping ftrace buffer: [ 33.715124] (ftrace buffer empty) [ 33.718867] Kernel Offset: disabled [ 33.722476] Rebooting in 86400 seconds..