[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.675708] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.450405] random: sshd: uninitialized urandom read (32 bytes read) [ 18.697539] random: sshd: uninitialized urandom read (32 bytes read) [ 19.212400] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.50' (ECDSA) to the list of known hosts. [ 24.907535] urandom_read: 1 callbacks suppressed [ 24.907538] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.092894] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.101646] IP: [] l2tp_session_free+0x11c/0x200 [ 25.108158] PGD 1b792e067 [ 25.110812] PUD 1c42c3067 PMD 0 [ 25.114319] [ 25.115956] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.120450] Dumping ftrace buffer: [ 25.124260] (ftrace buffer empty) [ 25.127959] Modules linked in: [ 25.131343] CPU: 1 PID: 3795 Comm: syz-executor756 Not tainted 4.9.120-gf85543b #76 [ 25.139181] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.148525] task: ffff8801b7903000 task.stack: ffff8801b9628000 [ 25.154566] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.163678] RSP: 0018:ffff8801b962fca0 EFLAGS: 00010246 [ 25.169117] RAX: dffffc0000000000 RBX: ffff8801b72d5400 RCX: 0000000000000000 [ 25.176376] RDX: 1ffff10036d83f00 RSI: ffffffff836c29a1 RDI: ffff8801b6c1f800 [ 25.183633] RBP: ffff8801b962fcc0 R08: ffff8801b79038e8 R09: 0000000000000000 [ 25.190887] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6c1f680 [ 25.198151] R13: ffff8801b72d5408 R14: 0000000000000000 R15: ffffffff83018be0 [ 25.205547] FS: 0000000001982880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 25.213767] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.219642] CR2: 0000000000000080 CR3: 00000001b97e9000 CR4: 00000000001606f0 [ 25.226909] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.234174] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.241446] Stack: [ 25.243586] ffff8801b6352200 ffff8801b72d5400 ffff8801b63525d0 ffff8801b63524d8 [ 25.251762] ffff8801b962fce8 ffffffff836ca2b2 ffff8801b6352640 ffff8801b6352200 [ 25.259871] ffffffff836ca1e0 ffff8801b962fd20 ffffffff830260f5 ffff8801b6352640 [ 25.267960] Call Trace: [ 25.270540] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.277199] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.283509] [] __sk_destruct+0x55/0x590 [ 25.289128] [] ? sock_release+0x1c0/0x1c0 [ 25.294917] [] sk_destruct+0x63/0x80 [ 25.300334] [] __sk_free+0x4f/0x220 [ 25.305604] [] sk_free+0x2b/0x40 [ 25.310611] [] pppol2tp_release+0x239/0x2e0 [ 25.316687] [] sock_release+0x96/0x1c0 [ 25.322218] [] sock_close+0x16/0x20 [ 25.327489] [] __fput+0x263/0x700 [ 25.332695] [] ____fput+0x15/0x20 [ 25.337788] [] task_work_run+0x10c/0x180 [ 25.343491] [] exit_to_usermode_loop+0xfc/0x120 [ 25.349801] [] do_syscall_64+0x364/0x490 [ 25.355504] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.362416] 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 [ 25.390462] RIP [] l2tp_session_free+0x11c/0x200 [ 25.396996] RSP [ 25.400608] CR2: 0000000000000080 [ 25.404708] ---[ end trace 43a4cd8d6e16ff36 ]--- [ 25.409560] Kernel panic - not syncing: Fatal exception [ 25.415568] Dumping ftrace buffer: [ 25.419121] (ftrace buffer empty) [ 25.422820] Kernel Offset: disabled [ 25.426437] Rebooting in 86400 seconds..