[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.931048] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.196439] random: sshd: uninitialized urandom read (32 bytes read) [ 15.518624] random: sshd: uninitialized urandom read (32 bytes read) [ 16.465418] random: sshd: uninitialized urandom read (32 bytes read) [ 16.604503] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.194' (ECDSA) to the list of known hosts. [ 22.248611] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 22.472052] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 22.480319] IP: [] l2tp_session_free+0x11c/0x200 [ 22.486788] PGD 1c41fb067 [ 22.489442] PUD 1c417f067 PMD 0 [ 22.492942] [ 22.494617] Oops: 0002 [#1] PREEMPT SMP KASAN [ 22.499098] Dumping ftrace buffer: [ 22.502629] (ftrace buffer empty) [ 22.506339] Modules linked in: [ 22.509673] CPU: 1 PID: 3788 Comm: syz-executor704 Not tainted 4.9.113-g47bbcd6 #62 [ 22.517459] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 22.526837] task: ffff8801b9e54800 task.stack: ffff8801c1ee8000 [ 22.532878] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 22.541742] RSP: 0018:ffff8801c1eefca0 EFLAGS: 00010246 [ 22.547170] RAX: dffffc0000000000 RBX: ffff8801cad5aa00 RCX: 0000000000000000 [ 22.554423] RDX: 1ffff100394e4dc0 RSI: ffffffff836bcce1 RDI: ffff8801ca726e00 [ 22.561673] RBP: ffff8801c1eefcc0 R08: ffff8801b9e550e8 R09: 0000000000000000 [ 22.568927] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ca726c80 [ 22.576198] R13: ffff8801cad5aa08 R14: 0000000000000000 R15: ffffffff83013be0 [ 22.583451] FS: 0000000000b72880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 22.591668] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 22.597530] CR2: 0000000000000080 CR3: 00000001c4205000 CR4: 00000000001606f0 [ 22.604784] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 22.612042] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 22.619298] Stack: [ 22.621448] ffff8801d91e4400 ffff8801cad5aa00 ffff8801d91e47d0 ffff8801d91e46d8 [ 22.629473] ffff8801c1eefce8 ffffffff836c45f2 ffff8801d91e4840 ffff8801d91e4400 [ 22.637523] ffffffff836c4520 ffff8801c1eefd20 ffffffff83021095 ffff8801d91e4840 [ 22.645563] Call Trace: [ 22.648136] [] pppol2tp_session_destruct+0xd2/0x110 [ 22.654782] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 22.661092] [] __sk_destruct+0x55/0x590 [ 22.666700] [] ? sock_release+0x1c0/0x1c0 [ 22.672484] [] sk_destruct+0x63/0x80 [ 22.677844] [] __sk_free+0x4f/0x220 [ 22.683106] [] sk_free+0x2b/0x40 [ 22.688116] [] pppol2tp_release+0x239/0x2e0 [ 22.694091] [] sock_release+0x96/0x1c0 [ 22.699622] [] sock_close+0x16/0x20 [ 22.704897] [] __fput+0x263/0x700 [ 22.709981] [] ____fput+0x15/0x20 [ 22.715082] [] task_work_run+0x10c/0x180 [ 22.720779] [] exit_to_usermode_loop+0xfc/0x120 [ 22.727087] [] do_syscall_64+0x364/0x490 [ 22.732783] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 22.739690] 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 [ 22.767213] RIP [] l2tp_session_free+0x11c/0x200 [ 22.773790] RSP [ 22.777400] CR2: 0000000000000080 [ 22.781110] ---[ end trace 1960bd682d46942f ]--- [ 22.785887] Kernel panic - not syncing: Fatal exception [ 22.791859] Dumping ftrace buffer: [ 22.795389] (ftrace buffer empty) [ 22.799078] Kernel Offset: disabled [ 22.802685] Rebooting in 86400 seconds..