[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.079069] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.223886] random: sshd: uninitialized urandom read (32 bytes read) [ 20.580729] random: sshd: uninitialized urandom read (32 bytes read) [ 21.545849] random: sshd: uninitialized urandom read (32 bytes read) [ 21.674840] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.25' (ECDSA) to the list of known hosts. [ 27.375499] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.584668] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.592953] IP: [] l2tp_session_free+0x11c/0x200 [ 27.599404] PGD 1ca02b067 [ 27.602051] PUD 1c5d1d067 PMD 0 [ 27.605524] [ 27.607144] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.611612] Dumping ftrace buffer: [ 27.615122] (ftrace buffer empty) [ 27.618820] Modules linked in: [ 27.622117] CPU: 0 PID: 3802 Comm: syz-executor608 Not tainted 4.9.113-g47bbcd6 #10 [ 27.629879] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.639208] task: ffff8801b5811800 task.stack: ffff8801d92e8000 [ 27.645255] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.654121] RSP: 0018:ffff8801d92efca0 EFLAGS: 00010246 [ 27.659545] RAX: dffffc0000000000 RBX: ffff8801ca5d4780 RCX: 0000000000000000 [ 27.666885] RDX: 1ffff10036bd4830 RSI: ffffffff836bcce1 RDI: ffff8801b5ea4180 [ 27.674128] RBP: ffff8801d92efcc0 R08: ffff8801b58120e8 R09: 0000000000000000 [ 27.681371] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5ea4000 [ 27.688620] R13: ffff8801ca5d4788 R14: 0000000000000000 R15: ffffffff83013be0 [ 27.695880] FS: 0000000000838880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 27.704080] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.709942] CR2: 0000000000000080 CR3: 00000001bd947000 CR4: 00000000001606f0 [ 27.717204] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.724456] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.731702] Stack: [ 27.733837] ffff8801d9333300 ffff8801ca5d4780 ffff8801d93336d0 ffff8801d93335d8 [ 27.741831] ffff8801d92efce8 ffffffff836c45f2 ffff8801d9333740 ffff8801d9333300 [ 27.749811] ffffffff836c4520 ffff8801d92efd20 ffffffff83021095 ffff8801d9333740 [ 27.757790] Call Trace: [ 27.760360] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.767007] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.773314] [] __sk_destruct+0x55/0x590 [ 27.778914] [] ? sock_release+0x1c0/0x1c0 [ 27.784687] [] sk_destruct+0x63/0x80 [ 27.790024] [] __sk_free+0x4f/0x220 [ 27.795272] [] sk_free+0x2b/0x40 [ 27.800265] [] pppol2tp_release+0x239/0x2e0 [ 27.806220] [] sock_release+0x96/0x1c0 [ 27.811743] [] sock_close+0x16/0x20 [ 27.817004] [] __fput+0x263/0x700 [ 27.822080] [] ____fput+0x15/0x20 [ 27.827161] [] task_work_run+0x10c/0x180 [ 27.832845] [] exit_to_usermode_loop+0xfc/0x120 [ 27.839138] [] do_syscall_64+0x364/0x490 [ 27.844832] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.851740] 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 [ 27.878598] RIP [] l2tp_session_free+0x11c/0x200 [ 27.885208] RSP [ 27.888804] CR2: 0000000000000080 [ 27.895073] ---[ end trace 70020622ec54c0d6 ]--- [ 27.899819] Kernel panic - not syncing: Fatal exception [ 27.905624] Dumping ftrace buffer: [ 27.909147] (ftrace buffer empty) [ 27.912893] Kernel Offset: disabled [ 27.916492] Rebooting in 86400 seconds..