[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.666728] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.090161] random: sshd: uninitialized urandom read (32 bytes read) [ 19.471940] random: sshd: uninitialized urandom read (32 bytes read) [ 19.985688] random: sshd: uninitialized urandom read (32 bytes read) [ 20.128817] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.14' (ECDSA) to the list of known hosts. [ 25.550182] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.779205] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.787444] IP: [] l2tp_session_free+0x11c/0x200 [ 25.793870] PGD 1c92ff067 [ 25.796528] PUD 1c3b4b067 PMD 0 [ 25.800007] [ 25.801628] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.806104] Dumping ftrace buffer: [ 25.809619] (ftrace buffer empty) [ 25.813307] Modules linked in: [ 25.816604] CPU: 1 PID: 3805 Comm: syz-executor563 Not tainted 4.9.119-g9dc978d #75 [ 25.824368] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.833701] task: ffff8801b5adc800 task.stack: ffff8801d9058000 [ 25.839730] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.848584] RSP: 0018:ffff8801d905fca0 EFLAGS: 00010246 [ 25.854006] RAX: dffffc0000000000 RBX: ffff8801c91e3680 RCX: 0000000000000000 [ 25.861255] RDX: 1ffff1003925b5c0 RSI: ffffffff836bf9a1 RDI: ffff8801c92dae00 [ 25.868503] RBP: ffff8801d905fcc0 R08: ffff8801b5add0e8 R09: 0000000000000000 [ 25.875750] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c92dac80 [ 25.882999] R13: ffff8801c91e3688 R14: 0000000000000000 R15: ffffffff83015be0 [ 25.890257] FS: 000000000160c880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 25.898470] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.904331] CR2: 0000000000000080 CR3: 00000001c3b5d000 CR4: 00000000001606f0 [ 25.911585] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.918836] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.926085] Stack: [ 25.928228] ffff8801b6ff5d80 ffff8801c91e3680 ffff8801b6ff6150 ffff8801b6ff6058 [ 25.936256] ffff8801d905fce8 ffffffff836c72b2 ffff8801b6ff61c0 ffff8801b6ff5d80 [ 25.944284] ffffffff836c71e0 ffff8801d905fd20 ffffffff830230f5 ffff8801b6ff61c0 [ 25.952574] Call Trace: [ 25.955156] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.961805] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.968327] [] __sk_destruct+0x55/0x590 [ 25.974063] [] ? sock_release+0x1c0/0x1c0 [ 25.979848] [] sk_destruct+0x63/0x80 [ 25.985211] [] __sk_free+0x4f/0x220 [ 25.990473] [] sk_free+0x2b/0x40 [ 25.995591] [] pppol2tp_release+0x239/0x2e0 [ 26.001559] [] sock_release+0x96/0x1c0 [ 26.007086] [] sock_close+0x16/0x20 [ 26.012352] [] __fput+0x263/0x700 [ 26.017446] [] ____fput+0x15/0x20 [ 26.022654] [] task_work_run+0x10c/0x180 [ 26.028357] [] exit_to_usermode_loop+0xfc/0x120 [ 26.034662] [] do_syscall_64+0x364/0x490 [ 26.040359] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.047268] 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 [ 26.075541] RIP [] l2tp_session_free+0x11c/0x200 [ 26.082071] RSP [ 26.085963] CR2: 0000000000000080 [ 26.089515] ---[ end trace 74e1855ededcfae5 ]--- [ 26.094271] Kernel panic - not syncing: Fatal exception [ 26.100139] Dumping ftrace buffer: [ 26.103667] (ftrace buffer empty) [ 26.107453] Kernel Offset: disabled [ 26.111231] Rebooting in 86400 seconds..