[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.523690] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 14.214407] random: sshd: uninitialized urandom read (32 bytes read) [ 14.494946] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.009903] random: sshd: uninitialized urandom read (32 bytes read) [ 15.143104] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.57' (ECDSA) to the list of known hosts. [ 20.964202] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.165964] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.174212] IP: [] l2tp_session_free+0x11c/0x200 [ 21.180634] PGD 1ca9b7067 [ 21.183279] PUD 1ca9b3067 PMD 0 [ 21.186758] [ 21.188381] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.192848] Dumping ftrace buffer: [ 21.196361] (ftrace buffer empty) [ 21.200060] Modules linked in: [ 21.203350] CPU: 1 PID: 3667 Comm: syz-executor509 Not tainted 4.9.119-g9dc978d #23 [ 21.211134] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.220507] task: ffff8801c4100000 task.stack: ffff8801c2d90000 [ 21.226542] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.235392] RSP: 0018:ffff8801c2d97ca0 EFLAGS: 00010246 [ 21.240816] RAX: dffffc0000000000 RBX: ffff8801c3260c80 RCX: 0000000000000000 [ 21.248061] RDX: 1ffff100385b02b0 RSI: ffffffff836bf9a1 RDI: ffff8801c2d81580 [ 21.255304] RBP: ffff8801c2d97cc0 R08: ffff8801c41008e8 R09: 0000000000000000 [ 21.262548] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c2d81400 [ 21.269794] R13: ffff8801c3260c88 R14: 0000000000000000 R15: ffffffff83015be0 [ 21.277040] FS: 0000000000d9b880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 21.285239] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.291096] CR2: 0000000000000080 CR3: 00000001ca965000 CR4: 00000000001606f0 [ 21.298344] Stack: [ 21.300471] ffff8801c376ee80 ffff8801c3260c80 ffff8801c376f250 ffff8801c376f158 [ 21.308505] ffff8801c2d97ce8 ffffffff836c72b2 ffff8801c376f2c0 ffff8801c376ee80 [ 21.316504] ffffffff836c71e0 ffff8801c2d97d20 ffffffff830230f5 ffff8801c376f2c0 [ 21.324493] Call Trace: [ 21.327064] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.333707] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.340009] [] __sk_destruct+0x55/0x590 [ 21.345627] [] ? sock_release+0x1c0/0x1c0 [ 21.351402] [] sk_destruct+0x63/0x80 [ 21.356741] [] __sk_free+0x4f/0x220 [ 21.361999] [] sk_free+0x2b/0x40 [ 21.367002] [] pppol2tp_release+0x239/0x2e0 [ 21.372951] [] sock_release+0x96/0x1c0 [ 21.378462] [] sock_close+0x16/0x20 [ 21.383916] [] __fput+0x263/0x700 [ 21.389004] [] ____fput+0x15/0x20 [ 21.394090] [] task_work_run+0x10c/0x180 [ 21.399779] [] exit_to_usermode_loop+0xfc/0x120 [ 21.406073] [] do_syscall_64+0x364/0x490 [ 21.411758] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.418671] 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 f5 f0 c9 fd 4c 89 ea 48 b8 00 [ 21.445535] RIP [] l2tp_session_free+0x11c/0x200 [ 21.452039] RSP [ 21.455639] CR2: 0000000000000080 [ 21.459451] ---[ end trace f3b4c4701008ade2 ]--- [ 21.464222] Kernel panic - not syncing: Fatal exception [ 21.469881] Dumping ftrace buffer: [ 21.473403] (ftrace buffer empty) [ 21.477087] Kernel Offset: disabled [ 21.480690] Rebooting in 86400 seconds..