[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.146926] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 28.519800] random: sshd: uninitialized urandom read (32 bytes read) [ 29.025712] random: sshd: uninitialized urandom read (32 bytes read) [ 29.545479] random: sshd: uninitialized urandom read (32 bytes read) [ 29.684574] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.39' (ECDSA) to the list of known hosts. [ 35.395614] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 35.596148] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 35.604403] IP: [] l2tp_session_free+0x11c/0x200 [ 35.610822] PGD 1c26e8067 [ 35.613466] PUD 1c53a9067 PMD 0 [ 35.616952] [ 35.618575] Oops: 0002 [#1] PREEMPT SMP KASAN [ 35.623052] Dumping ftrace buffer: [ 35.626574] (ftrace buffer empty) [ 35.630260] Modules linked in: [ 35.633553] CPU: 1 PID: 3817 Comm: syz-executor576 Not tainted 4.9.123-g8dd3fc2 #27 [ 35.641316] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 35.650647] task: ffff8801b8898000 task.stack: ffff8801b5870000 [ 35.656681] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 35.665541] RSP: 0018:ffff8801b5877ca0 EFLAGS: 00010246 [ 35.670962] RAX: dffffc0000000000 RBX: ffff8801b5e4b900 RCX: 0000000000000000 [ 35.678210] RDX: 1ffff10036b39c80 RSI: ffffffff836c4991 RDI: ffff8801b59ce400 [ 35.685454] RBP: ffff8801b5877cc0 R08: ffff8801b88988e8 R09: 0000000000000000 [ 35.692707] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b59ce280 [ 35.699951] R13: ffff8801b5e4b908 R14: 0000000000000000 R15: ffffffff8301abe0 [ 35.707197] FS: 0000000001c4a880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 35.715397] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 35.721257] CR2: 0000000000000080 CR3: 00000001c262d000 CR4: 00000000001606f0 [ 35.728509] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 35.735865] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 35.743110] Stack: [ 35.745238] ffff8801b590e600 ffff8801b5e4b900 ffff8801b590e9d0 ffff8801b590e8d8 [ 35.753241] ffff8801b5877ce8 ffffffff836cc2a2 ffff8801b590ea40 ffff8801b590e600 [ 35.761246] ffffffff836cc1d0 ffff8801b5877d20 ffffffff830280f5 ffff8801b590ea40 [ 35.769245] Call Trace: [ 35.771814] [] pppol2tp_session_destruct+0xd2/0x110 [ 35.778454] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 35.784758] [] __sk_destruct+0x55/0x590 [ 35.790357] [] ? sock_release+0x1c0/0x1c0 [ 35.796133] [] sk_destruct+0x63/0x80 [ 35.801478] [] __sk_free+0x4f/0x220 [ 35.806732] [] sk_free+0x2b/0x40 [ 35.811725] [] pppol2tp_release+0x239/0x2e0 [ 35.817676] [] sock_release+0x96/0x1c0 [ 35.823189] [] sock_close+0x16/0x20 [ 35.828441] [] __fput+0x263/0x700 [ 35.833519] [] ____fput+0x15/0x20 [ 35.838606] [] task_work_run+0x10c/0x180 [ 35.844292] [] exit_to_usermode_loop+0xfc/0x120 [ 35.850585] [] do_syscall_64+0x364/0x490 [ 35.856277] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 35.863175] 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 e5 c3 c9 fd 4c 89 ea 48 b8 00 [ 35.890148] RIP [] l2tp_session_free+0x11c/0x200 [ 35.896659] RSP [ 35.900257] CR2: 0000000000000080 [ 35.904023] ---[ end trace d991814769135287 ]--- [ 35.908784] Kernel panic - not syncing: Fatal exception [ 35.914519] Dumping ftrace buffer: [ 35.918038] (ftrace buffer empty) [ 35.921788] Kernel Offset: disabled [ 35.925396] Rebooting in 86400 seconds..