[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.518747] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.108444] random: sshd: uninitialized urandom read (32 bytes read) [ 15.326495] random: sshd: uninitialized urandom read (32 bytes read) [ 15.890550] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.53' (ECDSA) to the list of known hosts. [ 21.461586] urandom_read: 1 callbacks suppressed [ 21.461589] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.657365] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.665614] IP: [<ffffffff836bf91c>] l2tp_session_free+0x11c/0x200 [ 21.672037] PGD 1bbba8067 [ 21.674680] PUD 1bbb70067 PMD 0 [ 21.678433] [ 21.680067] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.684536] Dumping ftrace buffer: [ 21.688048] (ftrace buffer empty) [ 21.691732] Modules linked in: [ 21.695046] CPU: 1 PID: 3793 Comm: syz-executor877 Not tainted 4.9.117-g8b21e85 #19 [ 21.702810] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.712146] task: ffff8801b8486000 task.stack: ffff8801b6978000 [ 21.718176] RIP: 0010:[<ffffffff836bf91c>] [<ffffffff836bf91c>] l2tp_session_free+0x11c/0x200 [ 21.727045] RSP: 0018:ffff8801b697fca0 EFLAGS: 00010246 [ 21.732477] RAX: dffffc0000000000 RBX: ffff8801b6a32780 RCX: 0000000000000000 [ 21.739732] RDX: 1ffff100393d7970 RSI: ffffffff836bf8f1 RDI: ffff8801c9ebcb80 [ 21.746988] RBP: ffff8801b697fcc0 R08: ffff8801b84868e8 R09: 0000000000000000 [ 21.754231] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9ebca00 [ 21.761484] R13: ffff8801b6a32788 R14: 0000000000000000 R15: ffffffff83015be0 [ 21.768735] FS: 00000000007fd880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 21.776944] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.782815] CR2: 0000000000000080 CR3: 00000001c521d000 CR4: 00000000001606f0 [ 21.790067] Stack: [ 21.792204] ffff8801b7fa3b80 ffff8801b6a32780 ffff8801b7fa3f50 ffff8801b7fa3e58 [ 21.800220] ffff8801b697fce8 ffffffff836c7202 ffff8801b7fa3fc0 ffff8801b7fa3b80 [ 21.808229] ffffffff836c7130 ffff8801b697fd20 ffffffff83023095 ffff8801b7fa3fc0 [ 21.816219] Call Trace: [ 21.818783] [<ffffffff836c7202>] pppol2tp_session_destruct+0xd2/0x110 [ 21.825423] [<ffffffff836c7130>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.831718] [<ffffffff83023095>] __sk_destruct+0x55/0x590 [ 21.837321] [<ffffffff83015be0>] ? sock_release+0x1c0/0x1c0 [ 21.843094] [<ffffffff8302ab23>] sk_destruct+0x63/0x80 [ 21.848443] [<ffffffff8302ab8f>] __sk_free+0x4f/0x220 [ 21.853696] [<ffffffff8302ad8b>] sk_free+0x2b/0x40 [ 21.858688] [<ffffffff836ca509>] pppol2tp_release+0x239/0x2e0 [ 21.864634] [<ffffffff83015ab6>] sock_release+0x96/0x1c0 [ 21.870160] [<ffffffff83015bf6>] sock_close+0x16/0x20 [ 21.875416] [<ffffffff81578693>] __fput+0x263/0x700 [ 21.880495] [<ffffffff81578bb5>] ____fput+0x15/0x20 [ 21.885583] [<ffffffff8119838c>] task_work_run+0x10c/0x180 [ 21.891268] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 21.897579] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 21.903279] [<ffffffff839fcc13>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.910187] 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 <f0> 41 ff 8e 80 00 00 00 74 69 e8 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 21.937159] RIP [<ffffffff836bf91c>] l2tp_session_free+0x11c/0x200 [ 21.943675] RSP <ffff8801b697fca0> [ 21.947272] CR2: 0000000000000080 [ 21.950810] ---[ end trace 19012807418bd2b7 ]--- [ 21.955580] Kernel panic - not syncing: Fatal exception [ 21.961215] Dumping ftrace buffer: [ 21.964734] (ftrace buffer empty) [ 21.968419] Kernel Offset: disabled [ 21.972017] Rebooting in 86400 seconds..