[....] 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[ 15.904556] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.605141] random: sshd: uninitialized urandom read (32 bytes read) [ 20.852400] random: sshd: uninitialized urandom read (32 bytes read) [ 21.349098] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.61' (ECDSA) to the list of known hosts. [ 27.252765] urandom_read: 1 callbacks suppressed [ 27.252769] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.499430] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.507641] IP: [] l2tp_session_free+0x11c/0x200 [ 27.514075] PGD 1c61ef067 [ 27.516719] PUD 1cb001067 PMD 0 [ 27.520206] [ 27.521826] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.526296] Dumping ftrace buffer: [ 27.529807] (ftrace buffer empty) [ 27.533493] Modules linked in: [ 27.536809] CPU: 1 PID: 3808 Comm: syz-executor159 Not tainted 4.9.124-g09eb2ba #31 [ 27.544578] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.553907] task: ffff8801b6809800 task.stack: ffff8801b5a00000 [ 27.559938] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.568793] RSP: 0018:ffff8801b5a07c98 EFLAGS: 00010246 [ 27.574221] RAX: dffffc0000000000 RBX: ffff8801b7214000 RCX: 0000000000000000 [ 27.581471] RDX: 1ffff10036bf47a0 RSI: ffffffff836c4711 RDI: ffff8801b5fa3d00 [ 27.588718] RBP: ffff8801b5a07cb8 R08: ffff8801b680a0e8 R09: 0000000000000000 [ 27.595966] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5fa3b80 [ 27.603216] R13: ffff8801b7214008 R14: 0000000000000000 R15: 0000000000000000 [ 27.610534] FS: 00000000025ab880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 27.618743] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.624599] CR2: 0000000000000080 CR3: 00000001c9b5c000 CR4: 00000000001606f0 [ 27.631850] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.639229] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.646542] Stack: [ 27.648675] ffff8801cb169100 ffff8801b7214000 ffff8801cb1694d0 ffff8801cb1693d8 [ 27.656718] ffff8801b5a07ce0 ffffffff836cc022 ffff8801cb169540 ffff8801cb169100 [ 27.664722] ffffffff836cbf50 ffff8801b5a07d18 ffffffff830281f5 ffff8801cb169540 [ 27.672710] Call Trace: [ 27.675275] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.681920] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.688229] [] __sk_destruct+0x55/0x590 [ 27.693838] [] sk_destruct+0x63/0x80 [ 27.699180] [] __sk_free+0x4f/0x220 [ 27.704439] [] sk_free+0x2b/0x40 [ 27.709537] [] pppol2tp_release+0x239/0x2e0 [ 27.715492] [] __sock_release+0xd7/0x260 [ 27.721232] [] ? __sock_release+0x260/0x260 [ 27.727185] [] sock_close+0x19/0x20 [ 27.732441] [] __fput+0x263/0x700 [ 27.737519] [] ____fput+0x15/0x20 [ 27.742600] [] task_work_run+0x10c/0x180 [ 27.748286] [] exit_to_usermode_loop+0xfc/0x120 [ 27.754580] [] do_syscall_64+0x364/0x490 [ 27.760265] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.767161] 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 [ 27.794138] RIP [] l2tp_session_free+0x11c/0x200 [ 27.800758] RSP [ 27.804361] CR2: 0000000000000080 [ 27.808118] ---[ end trace 98769957295d23e0 ]--- [ 27.812893] Kernel panic - not syncing: Fatal exception [ 27.818575] Dumping ftrace buffer: [ 27.822100] (ftrace buffer empty) [ 27.825784] Kernel Offset: disabled [ 27.829388] Rebooting in 86400 seconds..