[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.480955] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.472044] random: sshd: uninitialized urandom read (32 bytes read) [ 18.787350] random: sshd: uninitialized urandom read (32 bytes read) [ 19.329109] random: sshd: uninitialized urandom read (32 bytes read) [ 19.479089] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.57' (ECDSA) to the list of known hosts. [ 24.927771] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.127354] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.135584] IP: [] l2tp_session_free+0x11c/0x200 [ 25.142015] PGD 1ca27b067 [ 25.144661] PUD 1ca099067 PMD 0 [ 25.148167] [ 25.149805] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.154284] Dumping ftrace buffer: [ 25.157799] (ftrace buffer empty) [ 25.161485] Modules linked in: [ 25.164774] CPU: 0 PID: 3798 Comm: syz-executor775 Not tainted 4.9.119-g9dc978d #23 [ 25.172542] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.181878] task: ffff8801b6290000 task.stack: ffff8801b7c28000 [ 25.187911] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.196767] RSP: 0018:ffff8801b7c2fca0 EFLAGS: 00010246 [ 25.202189] RAX: dffffc0000000000 RBX: ffff8801b5d79900 RCX: 0000000000000000 [ 25.209501] RDX: 1ffff1003964f610 RSI: ffffffff836bf9a1 RDI: ffff8801cb27b080 [ 25.216818] RBP: ffff8801b7c2fcc0 R08: ffff8801b62908e8 R09: 0000000000000000 [ 25.224072] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb27af00 [ 25.231328] R13: ffff8801b5d79908 R14: 0000000000000000 R15: ffffffff83015be0 [ 25.238592] FS: 00000000007be880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 25.246843] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.252706] CR2: 0000000000000080 CR3: 00000001ca43d000 CR4: 00000000001606f0 [ 25.259956] Stack: [ 25.262089] ffff8801d946c400 ffff8801b5d79900 ffff8801d946c7d0 ffff8801d946c6d8 [ 25.270182] ffff8801b7c2fce8 ffffffff836c72b2 ffff8801d946c840 ffff8801d946c400 [ 25.278189] ffffffff836c71e0 ffff8801b7c2fd20 ffffffff830230f5 ffff8801d946c840 [ 25.286197] Call Trace: [ 25.288775] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.295432] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.301731] [] __sk_destruct+0x55/0x590 [ 25.307333] [] ? sock_release+0x1c0/0x1c0 [ 25.313108] [] sk_destruct+0x63/0x80 [ 25.318510] [] __sk_free+0x4f/0x220 [ 25.323785] [] sk_free+0x2b/0x40 [ 25.328782] [] pppol2tp_release+0x239/0x2e0 [ 25.334733] [] sock_release+0x96/0x1c0 [ 25.340261] [] sock_close+0x16/0x20 [ 25.345529] [] __fput+0x263/0x700 [ 25.350618] [] ____fput+0x15/0x20 [ 25.355719] [] task_work_run+0x10c/0x180 [ 25.361410] [] exit_to_usermode_loop+0xfc/0x120 [ 25.367714] [] do_syscall_64+0x364/0x490 [ 25.373417] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.380317] 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 [ 25.407569] RIP [] l2tp_session_free+0x11c/0x200 [ 25.414089] RSP [ 25.417709] CR2: 0000000000000080 [ 25.421264] ---[ end trace c202011bb1bc6ffe ]--- [ 25.426016] Kernel panic - not syncing: Fatal exception [ 25.431803] Dumping ftrace buffer: [ 25.435333] (ftrace buffer empty) [ 25.439019] Kernel Offset: disabled [ 25.442687] Rebooting in 86400 seconds..