[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.357653] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.310783] random: sshd: uninitialized urandom read (32 bytes read) [ 18.623192] random: sshd: uninitialized urandom read (32 bytes read) [ 19.602392] random: sshd: uninitialized urandom read (32 bytes read) [ 19.734628] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.22' (ECDSA) to the list of known hosts. [ 25.199216] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.394523] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.402764] IP: [] l2tp_session_free+0x11c/0x200 [ 25.409186] PGD 1c9fdc067 [ 25.411840] PUD 1c8a83067 PMD 0 [ 25.415322] [ 25.416945] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.421466] Dumping ftrace buffer: [ 25.424980] (ftrace buffer empty) [ 25.428665] Modules linked in: [ 25.431975] CPU: 0 PID: 3798 Comm: syz-executor805 Not tainted 4.9.116-g0137ea2 #18 [ 25.439743] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.449074] task: ffff8801b7de3000 task.stack: ffff8801bd078000 [ 25.455106] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.463966] RSP: 0018:ffff8801bd07fca0 EFLAGS: 00010246 [ 25.469394] RAX: dffffc0000000000 RBX: ffff8801ca534c80 RCX: 0000000000000000 [ 25.476641] RDX: 1ffff10036be4c30 RSI: ffffffff836be8f1 RDI: ffff8801b5f26180 [ 25.483885] RBP: ffff8801bd07fcc0 R08: ffff8801b7de38e8 R09: 0000000000000000 [ 25.491141] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5f26000 [ 25.498388] R13: ffff8801ca534c88 R14: 0000000000000000 R15: ffffffff83014be0 [ 25.505648] FS: 0000000001415880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 25.513849] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.519706] CR2: 0000000000000080 CR3: 00000001b958c000 CR4: 00000000001606f0 [ 25.526954] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.534210] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.541456] Stack: [ 25.543582] ffff8801bab68880 ffff8801ca534c80 ffff8801bab68c50 ffff8801bab68b58 [ 25.551577] ffff8801bd07fce8 ffffffff836c6202 ffff8801bab68cc0 ffff8801bab68880 [ 25.559611] ffffffff836c6130 ffff8801bd07fd20 ffffffff83022095 ffff8801bab68cc0 [ 25.567605] Call Trace: [ 25.570168] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.576821] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.583114] [] __sk_destruct+0x55/0x590 [ 25.588714] [] ? sock_release+0x1c0/0x1c0 [ 25.594485] [] sk_destruct+0x63/0x80 [ 25.599823] [] __sk_free+0x4f/0x220 [ 25.605073] [] sk_free+0x2b/0x40 [ 25.610064] [] pppol2tp_release+0x239/0x2e0 [ 25.616010] [] sock_release+0x96/0x1c0 [ 25.621610] [] sock_close+0x16/0x20 [ 25.626862] [] __fput+0x263/0x700 [ 25.631940] [] ____fput+0x15/0x20 [ 25.637027] [] task_work_run+0x10c/0x180 [ 25.642726] [] exit_to_usermode_loop+0xfc/0x120 [ 25.649017] [] do_syscall_64+0x364/0x490 [ 25.654705] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.661600] 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 65 01 ca fd 4c 89 ea 48 b8 00 [ 25.689151] RIP [] l2tp_session_free+0x11c/0x200 [ 25.695655] RSP [ 25.699263] CR2: 0000000000000080 [ 25.702982] ---[ end trace 4b93ff5e47e860ea ]--- [ 25.707759] Kernel panic - not syncing: Fatal exception [ 25.713545] Dumping ftrace buffer: [ 25.717067] (ftrace buffer empty) [ 25.720770] Kernel Offset: disabled [ 25.724375] Rebooting in 86400 seconds..