[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.509118] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 13.973883] random: sshd: uninitialized urandom read (32 bytes read) [ 14.206744] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.877266] random: sshd: uninitialized urandom read (32 bytes read) [ 15.072827] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.48' (ECDSA) to the list of known hosts. [ 20.602408] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 20.816052] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 20.824450] IP: [] l2tp_session_free+0x11c/0x200 [ 20.830934] PGD 1baf25067 [ 20.833648] PUD 1bb2a8067 PMD 0 [ 20.837170] [ 20.838881] Oops: 0002 [#1] PREEMPT SMP KASAN [ 20.843393] Dumping ftrace buffer: [ 20.846941] (ftrace buffer empty) [ 20.850646] Modules linked in: [ 20.853971] CPU: 1 PID: 3783 Comm: syz-executor793 Not tainted 4.9.119-g9dc978d #75 [ 20.861758] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 20.871117] task: ffff8801bb50e000 task.stack: ffff8801b8850000 [ 20.877320] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 20.886231] RSP: 0018:ffff8801b8857ca0 EFLAGS: 00010246 [ 20.891729] RAX: dffffc0000000000 RBX: ffff8801b88d8500 RCX: 0000000000000000 [ 20.899001] RDX: 1ffff1003711b300 RSI: ffffffff836bf9a1 RDI: ffff8801b88d9800 [ 20.906271] RBP: ffff8801b8857cc0 R08: ffff8801bb50e8e8 R09: 0000000000000000 [ 20.913556] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b88d9680 [ 20.920834] R13: ffff8801b88d8508 R14: 0000000000000000 R15: ffffffff83015be0 [ 20.928104] FS: 0000000002490880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 20.936330] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 20.942211] CR2: 0000000000000080 CR3: 00000001c8f99000 CR4: 00000000001606f0 [ 20.949487] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 20.956760] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 20.964026] Stack: [ 20.966174] ffff8801b8982200 ffff8801b88d8500 ffff8801b89825d0 ffff8801b89824d8 [ 20.974263] ffff8801b8857ce8 ffffffff836c72b2 ffff8801b8982640 ffff8801b8982200 [ 20.982329] ffffffff836c71e0 ffff8801b8857d20 ffffffff830230f5 ffff8801b8982640 [ 20.990394] Call Trace: [ 20.992984] [] pppol2tp_session_destruct+0xd2/0x110 [ 20.999655] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.005983] [] __sk_destruct+0x55/0x590 [ 21.011615] [] ? sock_release+0x1c0/0x1c0 [ 21.017422] [] sk_destruct+0x63/0x80 [ 21.022790] [] __sk_free+0x4f/0x220 [ 21.028071] [] sk_free+0x2b/0x40 [ 21.033102] [] pppol2tp_release+0x239/0x2e0 [ 21.039087] [] sock_release+0x96/0x1c0 [ 21.044632] [] sock_close+0x16/0x20 [ 21.050053] [] __fput+0x263/0x700 [ 21.055159] [] ____fput+0x15/0x20 [ 21.060266] [] task_work_run+0x10c/0x180 [ 21.066042] [] exit_to_usermode_loop+0xfc/0x120 [ 21.072378] [] do_syscall_64+0x364/0x490 [ 21.078100] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.085025] 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 [ 21.113488] RIP [] l2tp_session_free+0x11c/0x200 [ 21.120030] RSP [ 21.123650] CR2: 0000000000000080 [ 21.127416] ---[ end trace 4b7f1632a90c10c0 ]--- [ 21.132187] Kernel panic - not syncing: Fatal exception [ 21.138234] Dumping ftrace buffer: [ 21.141782] (ftrace buffer empty) [ 21.145484] Kernel Offset: disabled [ 21.150069] Rebooting in 86400 seconds..