[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.254233] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.496564] random: sshd: uninitialized urandom read (32 bytes read) [ 26.989835] random: sshd: uninitialized urandom read (32 bytes read) [ 27.700418] random: sshd: uninitialized urandom read (32 bytes read) [ 27.826380] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.32' (ECDSA) to the list of known hosts. [ 33.237837] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 33.441583] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 33.447824] IP: [ 33.447838] [] l2tp_session_free+0x11c/0x200 PGD 1c570f067 [ 33.447846] PUD 1bfae7067 [ 33.447847] PMD 0 [ 33.447847] [ 33.447853] Oops: 0002 [#1] PREEMPT SMP KASAN [ 33.447858] Dumping ftrace buffer: [ 33.447861] (ftrace buffer empty) [ 33.447865] Modules linked in: [ 33.447872] CPU: 1 PID: 3807 Comm: syz-executor480 Not tainted 4.9.113-g47bbcd6 #62 [ 33.447875] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.447879] task: ffff8801b748e000 task.stack: ffff8801d9888000 [ 33.447888] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 33.447891] RSP: 0018:ffff8801d988fca0 EFLAGS: 00010246 [ 33.447895] RAX: dffffc0000000000 RBX: ffff8801cbb07680 RCX: 0000000000000000 [ 33.447899] RDX: 1ffff10039769120 RSI: ffffffff836bcce1 RDI: ffff8801cbb48900 [ 33.447903] RBP: ffff8801d988fcc0 R08: ffff8801b748e8e8 R09: 0000000000000000 [ 33.447906] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cbb48780 [ 33.447910] R13: ffff8801cbb07688 R14: 0000000000000000 R15: ffffffff83013be0 [ 33.447915] FS: 000000000164a880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 33.447919] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 33.447922] CR2: 0000000000000080 CR3: 00000001be92f000 CR4: 00000000001606f0 [ 33.447929] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 33.447932] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 33.447934] Stack: [ 33.447943] ffff8801cb1dd500 ffff8801cbb07680 ffff8801cb1dd8d0 ffff8801cb1dd7d8 [ 33.447952] ffff8801d988fce8 ffffffff836c45f2 ffff8801cb1dd940 ffff8801cb1dd500 [ 33.447960] ffffffff836c4520 ffff8801d988fd20 ffffffff83021095 ffff8801cb1dd940 [ 33.447962] Call Trace: [ 33.447971] [] pppol2tp_session_destruct+0xd2/0x110 [ 33.447977] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 33.447984] [] __sk_destruct+0x55/0x590 [ 33.447991] [] ? sock_release+0x1c0/0x1c0 [ 33.447997] [] sk_destruct+0x63/0x80 [ 33.448003] [] __sk_free+0x4f/0x220 [ 33.448009] [] sk_free+0x2b/0x40 [ 33.448015] [] pppol2tp_release+0x239/0x2e0 [ 33.448022] [] sock_release+0x96/0x1c0 [ 33.448028] [] sock_close+0x16/0x20 [ 33.448036] [] __fput+0x263/0x700 [ 33.448043] [] ____fput+0x15/0x20 [ 33.448053] [] task_work_run+0x10c/0x180 [ 33.448063] [] exit_to_usermode_loop+0xfc/0x120 [ 33.448068] [] do_syscall_64+0x364/0x490 [ 33.448076] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 33.448176] 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 [ 33.448183] RIP [] l2tp_session_free+0x11c/0x200 [ 33.448185] RSP [ 33.448187] CR2: 0000000000000080 [ 33.448834] ---[ end trace c73cb46aca89f35e ]--- [ 33.448838] Kernel panic - not syncing: Fatal exception [ 33.450364] Dumping ftrace buffer: [ 33.450366] (ftrace buffer empty) [ 33.450369] Kernel Offset: disabled [ 33.762270] Rebooting in 86400 seconds..