[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.688229] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.210637] random: sshd: uninitialized urandom read (32 bytes read) [ 17.571754] random: sshd: uninitialized urandom read (32 bytes read) [ 18.079547] random: sshd: uninitialized urandom read (32 bytes read) [ 18.219521] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.23' (ECDSA) to the list of known hosts. [ 23.735195] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.938021] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.946732] IP: [] l2tp_session_free+0x11c/0x200 [ 23.953346] PGD 1c87e7067 [ 23.956135] PUD 1c85e5067 PMD 0 [ 23.959810] [ 23.961453] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.965938] Dumping ftrace buffer: [ 23.969465] (ftrace buffer empty) [ 23.973167] Modules linked in: [ 23.976488] CPU: 0 PID: 3801 Comm: syz-executor898 Not tainted 4.9.119-g9dc978d #75 [ 23.984282] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.993641] task: ffff8801b5d4e000 task.stack: ffff8801b5de8000 [ 23.999726] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.008611] RSP: 0018:ffff8801b5defca0 EFLAGS: 00010246 [ 24.014050] RAX: dffffc0000000000 RBX: ffff8801cb38ac80 RCX: 0000000000000000 [ 24.021536] RDX: 1ffff1003961ccd0 RSI: ffffffff836bf9a1 RDI: ffff8801cb0e6680 [ 24.028798] RBP: ffff8801b5defcc0 R08: ffff8801b5d4e8e8 R09: 0000000000000000 [ 24.036077] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb0e6500 [ 24.043346] R13: ffff8801cb38ac88 R14: 0000000000000000 R15: ffffffff83015be0 [ 24.050607] FS: 0000000000adc880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 24.059043] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.065005] CR2: 0000000000000080 CR3: 00000001c7851000 CR4: 00000000001606f0 [ 24.072269] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 24.079698] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 24.086961] Stack: [ 24.089215] ffff8801b5eb1980 ffff8801cb38ac80 ffff8801b5eb1d50 ffff8801b5eb1c58 [ 24.097401] ffff8801b5defce8 ffffffff836c72b2 ffff8801b5eb1dc0 ffff8801b5eb1980 [ 24.105478] ffffffff836c71e0 ffff8801b5defd20 ffffffff830230f5 ffff8801b5eb1dc0 [ 24.113796] Call Trace: [ 24.116378] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.123033] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.129806] [] __sk_destruct+0x55/0x590 [ 24.135452] [] ? sock_release+0x1c0/0x1c0 [ 24.141369] [] sk_destruct+0x63/0x80 [ 24.146731] [] __sk_free+0x4f/0x220 [ 24.152011] [] sk_free+0x2b/0x40 [ 24.157105] [] pppol2tp_release+0x239/0x2e0 [ 24.163075] [] sock_release+0x96/0x1c0 [ 24.168607] [] sock_close+0x16/0x20 [ 24.173875] [] __fput+0x263/0x700 [ 24.178968] [] ____fput+0x15/0x20 [ 24.184061] [] task_work_run+0x10c/0x180 [ 24.189763] [] exit_to_usermode_loop+0xfc/0x120 [ 24.196073] [] do_syscall_64+0x364/0x490 [ 24.201793] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.208716] 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 [ 24.237878] RIP [] l2tp_session_free+0x11c/0x200 [ 24.244447] RSP [ 24.248059] CR2: 0000000000000080 [ 24.252384] ---[ end trace 1b14a613a83c618d ]--- [ 24.257154] Kernel panic - not syncing: Fatal exception [ 24.263087] Dumping ftrace buffer: [ 24.266625] (ftrace buffer empty) [ 24.270487] Kernel Offset: disabled [ 24.274105] Rebooting in 86400 seconds..