[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.312004] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.119233] random: sshd: uninitialized urandom read (32 bytes read) [ 16.542708] random: sshd: uninitialized urandom read (32 bytes read) [ 17.449679] random: sshd: uninitialized urandom read (32 bytes read) [ 17.583754] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.7' (ECDSA) to the list of known hosts. [ 23.051919] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.272467] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.280723] IP: [] l2tp_session_free+0x11c/0x200 [ 23.287150] PGD 1c981b067 [ 23.289795] PUD 1caef3067 PMD 0 [ 23.293399] [ 23.295037] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.299511] Dumping ftrace buffer: [ 23.303030] (ftrace buffer empty) [ 23.306717] Modules linked in: [ 23.310066] CPU: 1 PID: 3800 Comm: syz-executor653 Not tainted 4.9.113-g47bbcd6 #62 [ 23.317839] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.327195] task: ffff8801b79fe000 task.stack: ffff8801c7dc8000 [ 23.333232] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.342105] RSP: 0018:ffff8801c7dcfca0 EFLAGS: 00010246 [ 23.347538] RAX: dffffc0000000000 RBX: ffff8801b5e7c280 RCX: 0000000000000000 [ 23.354822] RDX: 1ffff10036b2ad20 RSI: ffffffff836bcce1 RDI: ffff8801b5956900 [ 23.362071] RBP: ffff8801c7dcfcc0 R08: ffff8801b79fe8e8 R09: 0000000000000000 [ 23.369320] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5956780 [ 23.376574] R13: ffff8801b5e7c288 R14: 0000000000000000 R15: ffffffff83013be0 [ 23.383830] FS: 0000000001174880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 23.392036] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.397896] CR2: 0000000000000080 CR3: 00000001c9816000 CR4: 00000000001606f0 [ 23.405150] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.412404] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.419652] Stack: [ 23.421775] ffff8801c0f5c400 ffff8801b5e7c280 ffff8801c0f5c7d0 ffff8801c0f5c6d8 [ 23.429771] ffff8801c7dcfce8 ffffffff836c45f2 ffff8801c0f5c840 ffff8801c0f5c400 [ 23.437754] ffffffff836c4520 ffff8801c7dcfd20 ffffffff83021095 ffff8801c0f5c840 [ 23.445762] Call Trace: [ 23.448331] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.454989] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.461290] [] __sk_destruct+0x55/0x590 [ 23.466889] [] ? sock_release+0x1c0/0x1c0 [ 23.472660] [] sk_destruct+0x63/0x80 [ 23.478003] [] __sk_free+0x4f/0x220 [ 23.483264] [] sk_free+0x2b/0x40 [ 23.483270] [] pppol2tp_release+0x239/0x2e0 [ 23.483275] [] sock_release+0x96/0x1c0 [ 23.483279] [] sock_close+0x16/0x20 [ 23.483286] [] __fput+0x263/0x700 [ 23.483290] [] ____fput+0x15/0x20 [ 23.483297] [] task_work_run+0x10c/0x180 [ 23.483307] [] exit_to_usermode_loop+0xfc/0x120 [ 23.483311] [] do_syscall_64+0x364/0x490 [ 23.483317] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.483383] 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 55 1d ca fd 4c 89 ea 48 b8 00 [ 23.483388] RIP [] l2tp_session_free+0x11c/0x200 [ 23.483389] RSP [ 23.483391] CR2: 0000000000000080 [ 23.485239] ---[ end trace 14659d03e2b42a62 ]--- [ 23.485242] Kernel panic - not syncing: Fatal exception [ 23.488715] Dumping ftrace buffer: [ 23.488718] (ftrace buffer empty) [ 23.488720] Kernel Offset: disabled [ 23.593557] Rebooting in 86400 seconds..