[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.892047] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.638889] random: sshd: uninitialized urandom read (32 bytes read) [ 27.130023] random: sshd: uninitialized urandom read (32 bytes read) [ 27.612140] random: sshd: uninitialized urandom read (32 bytes read) [ 32.813888] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.55' (ECDSA) to the list of known hosts. [ 38.379409] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 38.578432] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 38.586643] IP: [] l2tp_session_free+0x11c/0x200 [ 38.593069] PGD 1c6798067 [ 38.595710] PUD 1c474b067 PMD 0 [ 38.599189] [ 38.600807] Oops: 0002 [#1] PREEMPT SMP KASAN [ 38.605279] Dumping ftrace buffer: [ 38.608796] (ftrace buffer empty) [ 38.612482] Modules linked in: [ 38.615779] CPU: 1 PID: 3811 Comm: syz-executor752 Not tainted 4.9.122-g54068d6 #26 [ 38.623541] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 38.632866] task: ffff8801b7eeb000 task.stack: ffff8801d9120000 [ 38.638899] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 38.647749] RSP: 0018:ffff8801d9127ca0 EFLAGS: 00010246 [ 38.653171] RAX: dffffc0000000000 RBX: ffff8801b9243b80 RCX: 0000000000000000 [ 38.660416] RDX: 1ffff10036e69eb0 RSI: ffffffff836c39a1 RDI: ffff8801b734f580 [ 38.667665] RBP: ffff8801d9127cc0 R08: ffff8801b7eeb8e8 R09: 0000000000000000 [ 38.674915] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b734f400 [ 38.682197] R13: ffff8801b9243b88 R14: 0000000000000000 R15: ffffffff83019be0 [ 38.689447] FS: 00000000007f5880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 38.697910] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 38.703765] CR2: 0000000000000080 CR3: 00000001b8475000 CR4: 00000000001606f0 [ 38.711007] Stack: [ 38.713130] ffff8801b659e600 ffff8801b9243b80 ffff8801b659e9d0 ffff8801b659e8d8 [ 38.721119] ffff8801d9127ce8 ffffffff836cb2b2 ffff8801b659ea40 ffff8801b659e600 [ 38.729169] ffffffff836cb1e0 ffff8801d9127d20 ffffffff830270f5 ffff8801b659ea40 [ 38.737350] Call Trace: [ 38.739919] [] pppol2tp_session_destruct+0xd2/0x110 [ 38.746566] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 38.752962] [] __sk_destruct+0x55/0x590 [ 38.758567] [] ? sock_release+0x1c0/0x1c0 [ 38.764346] [] sk_destruct+0x63/0x80 [ 38.769697] [] __sk_free+0x4f/0x220 [ 38.774965] [] sk_free+0x2b/0x40 [ 38.779964] [] pppol2tp_release+0x239/0x2e0 [ 38.785918] [] sock_release+0x96/0x1c0 [ 38.791433] [] sock_close+0x16/0x20 [ 38.796761] [] __fput+0x263/0x700 [ 38.801850] [] ____fput+0x15/0x20 [ 38.806935] [] task_work_run+0x10c/0x180 [ 38.812637] [] exit_to_usermode_loop+0xfc/0x120 [ 38.818935] [] do_syscall_64+0x364/0x490 [ 38.824624] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 38.831653] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 38.858770] RIP [] l2tp_session_free+0x11c/0x200 [ 38.865395] RSP [ 38.868998] CR2: 0000000000000080 [ 38.872763] ---[ end trace 43e2188c0fee0987 ]--- [ 38.877545] Kernel panic - not syncing: Fatal exception [ 38.883187] Dumping ftrace buffer: [ 38.886828] (ftrace buffer empty) [ 38.890517] Kernel Offset: disabled [ 38.894122] Rebooting in 86400 seconds..