[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.932853] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.912678] random: sshd: uninitialized urandom read (32 bytes read) [ 20.222010] random: sshd: uninitialized urandom read (32 bytes read) [ 21.160402] random: sshd: uninitialized urandom read (32 bytes read) [ 22.295668] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.16' (ECDSA) to the list of known hosts. [ 27.704946] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.917450] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.925687] IP: [] l2tp_session_free+0x11c/0x200 [ 27.932107] PGD 1c9a60067 [ 27.934746] PUD 1c9b12067 PMD 0 [ 27.938220] [ 27.939844] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.944313] Dumping ftrace buffer: [ 27.947823] (ftrace buffer empty) [ 27.951510] Modules linked in: [ 27.954797] CPU: 0 PID: 3789 Comm: syz-executor658 Not tainted 4.9.113-g47bbcd6 #62 [ 27.962558] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.971887] task: ffff8801b9d93000 task.stack: ffff8801d97f8000 [ 27.977914] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.986775] RSP: 0018:ffff8801d97ffca0 EFLAGS: 00010246 [ 27.992194] RAX: dffffc0000000000 RBX: ffff8801b9e96780 RCX: 0000000000000000 [ 27.999435] RDX: 1ffff100394d1080 RSI: ffffffff836bcce1 RDI: ffff8801ca688400 [ 28.006675] RBP: ffff8801d97ffcc0 R08: ffff8801b9d938e8 R09: 0000000000000000 [ 28.013917] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ca688280 [ 28.021170] R13: ffff8801b9e96788 R14: 0000000000000000 R15: ffffffff83013be0 [ 28.028413] FS: 00000000023a8880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 28.036612] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.042464] CR2: 0000000000000080 CR3: 00000001c1502000 CR4: 00000000001606f0 [ 28.049707] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.056959] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.064200] Stack: [ 28.066324] ffff8801d93aaa80 ffff8801b9e96780 ffff8801d93aae50 ffff8801d93aad58 [ 28.074327] ffff8801d97ffce8 ffffffff836c45f2 ffff8801d93aaec0 ffff8801d93aaa80 [ 28.082325] ffffffff836c4520 ffff8801d97ffd20 ffffffff83021095 ffff8801d93aaec0 [ 28.090314] Call Trace: [ 28.092881] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.099518] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.105820] [] __sk_destruct+0x55/0x590 [ 28.111427] [] ? sock_release+0x1c0/0x1c0 [ 28.117202] [] sk_destruct+0x63/0x80 [ 28.122539] [] __sk_free+0x4f/0x220 [ 28.127786] [] sk_free+0x2b/0x40 [ 28.132779] [] pppol2tp_release+0x239/0x2e0 [ 28.138725] [] sock_release+0x96/0x1c0 [ 28.144238] [] sock_close+0x16/0x20 [ 28.149489] [] __fput+0x263/0x700 [ 28.154563] [] ____fput+0x15/0x20 [ 28.159637] [] task_work_run+0x10c/0x180 [ 28.165337] [] exit_to_usermode_loop+0xfc/0x120 [ 28.171628] [] do_syscall_64+0x364/0x490 [ 28.177316] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.184218] 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 55 1d ca fd 4c 89 ea 48 b8 00 [ 28.211093] RIP [] l2tp_session_free+0x11c/0x200 [ 28.217605] RSP [ 28.221213] CR2: 0000000000000080 [ 28.224705] ---[ end trace 458a119ad7bc45f5 ]--- [ 28.229459] Kernel panic - not syncing: Fatal exception [ 28.235201] Dumping ftrace buffer: [ 28.238721] (ftrace buffer empty) [ 28.242402] Kernel Offset: disabled [ 28.246001] Rebooting in 86400 seconds..