[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.957388] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.885398] random: sshd: uninitialized urandom read (32 bytes read) [ 16.257063] random: sshd: uninitialized urandom read (32 bytes read) [ 16.755623] random: sshd: uninitialized urandom read (32 bytes read) [ 20.353934] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.34' (ECDSA) to the list of known hosts. [ 25.988598] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.211239] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.219684] IP: [] l2tp_session_free+0x11c/0x200 [ 26.226276] PGD 1c9efb067 [ 26.229060] PUD 1c9c1b067 PMD 0 [ 26.232726] [ 26.234375] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.238873] Dumping ftrace buffer: [ 26.242409] (ftrace buffer empty) [ 26.246226] Modules linked in: [ 26.249569] CPU: 1 PID: 3788 Comm: syz-executor226 Not tainted 4.9.119-g9dc978d #23 [ 26.257504] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.266852] task: ffff8801ba4c8000 task.stack: ffff8801b9060000 [ 26.273066] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 26.282164] RSP: 0018:ffff8801b9067ca0 EFLAGS: 00010246 [ 26.287604] RAX: dffffc0000000000 RBX: ffff8801b9795180 RCX: 0000000000000000 [ 26.295183] RDX: 1ffff10037243c30 RSI: ffffffff836bf9a1 RDI: ffff8801b921e180 [ 26.302561] RBP: ffff8801b9067cc0 R08: ffff8801ba4c88e8 R09: 0000000000000000 [ 26.309992] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b921e000 [ 26.317660] R13: ffff8801b9795188 R14: 0000000000000000 R15: ffffffff83015be0 [ 26.324922] FS: 0000000001ff9880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 26.333255] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.339254] CR2: 0000000000000080 CR3: 00000001c9dbe000 CR4: 00000000001606f0 [ 26.346519] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 26.353957] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 26.361218] Stack: [ 26.363366] ffff8801b90a9980 ffff8801b9795180 ffff8801b90a9d50 ffff8801b90a9c58 [ 26.371969] ffff8801b9067ce8 ffffffff836c72b2 ffff8801b90a9dc0 ffff8801b90a9980 [ 26.380410] ffffffff836c71e0 ffff8801b9067d20 ffffffff830230f5 ffff8801b90a9dc0 [ 26.388629] Call Trace: [ 26.391214] [] pppol2tp_session_destruct+0xd2/0x110 [ 26.398054] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.404485] [] __sk_destruct+0x55/0x590 [ 26.410454] [] ? sock_release+0x1c0/0x1c0 [ 26.416384] [] sk_destruct+0x63/0x80 [ 26.421951] [] __sk_free+0x4f/0x220 [ 26.427607] [] sk_free+0x2b/0x40 [ 26.432926] [] pppol2tp_release+0x239/0x2e0 [ 26.438892] [] sock_release+0x96/0x1c0 [ 26.444418] [] sock_close+0x16/0x20 [ 26.449779] [] __fput+0x263/0x700 [ 26.455031] [] ____fput+0x15/0x20 [ 26.460134] [] task_work_run+0x10c/0x180 [ 26.465839] [] exit_to_usermode_loop+0xfc/0x120 [ 26.472149] [] do_syscall_64+0x364/0x490 [ 26.477858] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.484919] 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 [ 26.513761] RIP [] l2tp_session_free+0x11c/0x200 [ 26.520426] RSP [ 26.524060] CR2: 0000000000000080 [ 26.527689] ---[ end trace 2118a3c04a955d68 ]--- [ 26.532563] Kernel panic - not syncing: Fatal exception [ 26.538522] Dumping ftrace buffer: [ 26.542059] (ftrace buffer empty) [ 26.545757] Kernel Offset: disabled [ 26.549540] Rebooting in 86400 seconds..