[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.210602] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.321788] random: sshd: uninitialized urandom read (32 bytes read) [ 17.679481] random: sshd: uninitialized urandom read (32 bytes read) [ 18.203069] random: sshd: uninitialized urandom read (32 bytes read) [ 18.351539] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.197' (ECDSA) to the list of known hosts. [ 23.828355] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.040297] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.048735] IP: [] l2tp_session_free+0x11c/0x200 [ 24.055226] PGD 1ca431067 [ 24.057909] PUD 1ca42e067 PMD 0 [ 24.061496] [ 24.063148] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.067727] Dumping ftrace buffer: [ 24.071434] (ftrace buffer empty) [ 24.075135] Modules linked in: [ 24.078503] CPU: 0 PID: 3788 Comm: syz-executor771 Not tainted 4.9.119-g9dc978d #23 [ 24.086289] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.095749] task: ffff8801bc3e8000 task.stack: ffff8801b9ba8000 [ 24.101786] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.110843] RSP: 0018:ffff8801b9bafca0 EFLAGS: 00010246 [ 24.116274] RAX: dffffc0000000000 RBX: ffff8801cb665b80 RCX: 0000000000000000 [ 24.123522] RDX: 1ffff1003728a260 RSI: ffffffff836bf9a1 RDI: ffff8801b9451300 [ 24.130906] RBP: ffff8801b9bafcc0 R08: ffff8801bc3e88e8 R09: 0000000000000000 [ 24.138158] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b9451180 [ 24.145435] R13: ffff8801cb665b88 R14: 0000000000000000 R15: ffffffff83015be0 [ 24.152815] FS: 0000000000f59880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 24.161147] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.167109] CR2: 0000000000000080 CR3: 00000001cad72000 CR4: 00000000001606f0 [ 24.174359] Stack: [ 24.176489] ffff8801cb950880 ffff8801cb665b80 ffff8801cb950c50 ffff8801cb950b58 [ 24.184632] ffff8801b9bafce8 ffffffff836c72b2 ffff8801cb950cc0 ffff8801cb950880 [ 24.192619] ffffffff836c71e0 ffff8801b9bafd20 ffffffff830230f5 ffff8801cb950cc0 [ 24.200685] Call Trace: [ 24.203265] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.209909] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.216318] [] __sk_destruct+0x55/0x590 [ 24.221921] [] ? sock_release+0x1c0/0x1c0 [ 24.227704] [] sk_destruct+0x63/0x80 [ 24.233162] [] __sk_free+0x4f/0x220 [ 24.238527] [] sk_free+0x2b/0x40 [ 24.243523] [] pppol2tp_release+0x239/0x2e0 [ 24.249469] [] sock_release+0x96/0x1c0 [ 24.255175] [] sock_close+0x16/0x20 [ 24.260484] [] __fput+0x263/0x700 [ 24.265633] [] ____fput+0x15/0x20 [ 24.270850] [] task_work_run+0x10c/0x180 [ 24.276543] [] exit_to_usermode_loop+0xfc/0x120 [ 24.282842] [] do_syscall_64+0x364/0x490 [ 24.288537] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.295593] 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 [ 24.322761] RIP [] l2tp_session_free+0x11c/0x200 [ 24.329269] RSP [ 24.332874] CR2: 0000000000000080 [ 24.336562] ---[ end trace ead60aa4907a39e6 ]--- [ 24.341317] Kernel panic - not syncing: Fatal exception [ 24.346922] Dumping ftrace buffer: [ 24.350440] (ftrace buffer empty) [ 24.354137] Kernel Offset: disabled [ 24.357745] Rebooting in 86400 seconds..