[....] 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[ 13.086923] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.538469] random: sshd: uninitialized urandom read (32 bytes read) [ 14.692271] random: sshd: uninitialized urandom read (32 bytes read) [ 15.202707] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.60' (ECDSA) to the list of known hosts. [ 21.055834] urandom_read: 1 callbacks suppressed [ 21.055837] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.259051] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.267284] IP: [] l2tp_session_free+0x11c/0x200 [ 21.273705] PGD 1bf867067 [ 21.276371] PUD 1ccde6067 PMD 0 [ 21.279854] [ 21.281485] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.285952] Dumping ftrace buffer: [ 21.289464] (ftrace buffer empty) [ 21.293149] Modules linked in: [ 21.296438] CPU: 0 PID: 3723 Comm: syz-executor438 Not tainted 4.9.124-g09eb2ba #83 [ 21.304203] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.313539] task: ffff8801bf881800 task.stack: ffff8801beef0000 [ 21.319566] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.328427] RSP: 0018:ffff8801beef7c98 EFLAGS: 00010246 [ 21.333860] RAX: dffffc0000000000 RBX: ffff8801bef7ef00 RCX: 0000000000000000 [ 21.341112] RDX: 1ffff10038030eb0 RSI: ffffffff836c4711 RDI: ffff8801c0187580 [ 21.348357] RBP: ffff8801beef7cb8 R08: ffff8801bf8820e8 R09: 0000000000000000 [ 21.355610] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c0187400 [ 21.362856] R13: ffff8801bef7ef08 R14: 0000000000000000 R15: 0000000000000000 [ 21.370101] FS: 0000000000f91880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 21.378310] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.384187] CR2: 0000000000000080 CR3: 00000001c8508000 CR4: 00000000001606f0 [ 21.391437] Stack: [ 21.393572] ffff8801cb5d2200 ffff8801bef7ef00 ffff8801cb5d25d0 ffff8801cb5d24d8 [ 21.401631] ffff8801beef7ce0 ffffffff836cc022 ffff8801cb5d2640 ffff8801cb5d2200 [ 21.409646] ffffffff836cbf50 ffff8801beef7d18 ffffffff830281f5 ffff8801cb5d2640 [ 21.417639] Call Trace: [ 21.420205] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.426852] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.433151] [] __sk_destruct+0x55/0x590 [ 21.438752] [] sk_destruct+0x63/0x80 [ 21.444100] [] __sk_free+0x4f/0x220 [ 21.449356] [] sk_free+0x2b/0x40 [ 21.454345] [] pppol2tp_release+0x239/0x2e0 [ 21.460293] [] __sock_release+0xd7/0x260 [ 21.465995] [] ? __sock_release+0x260/0x260 [ 21.472002] [] sock_close+0x19/0x20 [ 21.477258] [] __fput+0x263/0x700 [ 21.482337] [] ____fput+0x15/0x20 [ 21.487414] [] task_work_run+0x10c/0x180 [ 21.493101] [] exit_to_usermode_loop+0xfc/0x120 [ 21.499406] [] do_syscall_64+0x364/0x490 [ 21.505109] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.512007] 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 a5 c5 c9 fd 4c 89 ea 48 b8 00 [ 21.538992] RIP [] l2tp_session_free+0x11c/0x200 [ 21.545494] RSP [ 21.549093] CR2: 0000000000000080 [ 21.553212] ---[ end trace 2f078071b023abbf ]--- [ 21.557976] Kernel panic - not syncing: Fatal exception [ 21.563690] Dumping ftrace buffer: [ 21.567211] (ftrace buffer empty) [ 21.570896] Kernel Offset: disabled [ 21.574499] Rebooting in 86400 seconds..