[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.724770] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.536956] random: sshd: uninitialized urandom read (32 bytes read) [ 21.101766] random: sshd: uninitialized urandom read (32 bytes read) [ 22.055357] random: sshd: uninitialized urandom read (32 bytes read) [ 26.852999] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.29' (ECDSA) to the list of known hosts. [ 32.279816] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 32.474665] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 32.482922] IP: [] l2tp_session_free+0x11c/0x200 [ 32.489399] PGD 1c8376067 [ 32.492085] PUD 1c4db3067 PMD 0 [ 32.495603] [ 32.497230] Oops: 0002 [#1] PREEMPT SMP KASAN [ 32.501730] Dumping ftrace buffer: [ 32.505244] (ftrace buffer empty) [ 32.508928] Modules linked in: [ 32.512221] CPU: 1 PID: 3799 Comm: syz-executor114 Not tainted 4.9.113-g47bbcd6 #62 [ 32.519987] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 32.529320] task: ffff8801b883c800 task.stack: ffff8801d8c68000 [ 32.535347] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 32.544198] RSP: 0018:ffff8801d8c6fca0 EFLAGS: 00010246 [ 32.549621] RAX: dffffc0000000000 RBX: ffff8801c2615b80 RCX: 0000000000000000 [ 32.556866] RDX: 1ffff1003964e170 RSI: ffffffff836bcce1 RDI: ffff8801cb270b80 [ 32.564117] RBP: ffff8801d8c6fcc0 R08: ffff8801b883d0e8 R09: 0000000000000000 [ 32.571361] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb270a00 [ 32.578606] R13: ffff8801c2615b88 R14: 0000000000000000 R15: ffffffff83013be0 [ 32.585868] FS: 0000000000e56880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 32.594069] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 32.599924] CR2: 0000000000000080 CR3: 00000001c3e9a000 CR4: 00000000001606f0 [ 32.607172] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 32.614422] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 32.621667] Stack: [ 32.623792] ffff8801b6be3b80 ffff8801c2615b80 ffff8801b6be3f50 ffff8801b6be3e58 [ 32.631793] ffff8801d8c6fce8 ffffffff836c45f2 ffff8801b6be3fc0 ffff8801b6be3b80 [ 32.639800] ffffffff836c4520 ffff8801d8c6fd20 ffffffff83021095 ffff8801b6be3fc0 [ 32.647821] Call Trace: [ 32.650407] [] pppol2tp_session_destruct+0xd2/0x110 [ 32.657138] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 32.663438] [] __sk_destruct+0x55/0x590 [ 32.669046] [] ? sock_release+0x1c0/0x1c0 [ 32.674820] [] sk_destruct+0x63/0x80 [ 32.680162] [] __sk_free+0x4f/0x220 [ 32.685423] [] sk_free+0x2b/0x40 [ 32.690430] [] pppol2tp_release+0x239/0x2e0 [ 32.696390] [] sock_release+0x96/0x1c0 [ 32.701912] [] sock_close+0x16/0x20 [ 32.707171] [] __fput+0x263/0x700 [ 32.712251] [] ____fput+0x15/0x20 [ 32.717339] [] task_work_run+0x10c/0x180 [ 32.723027] [] exit_to_usermode_loop+0xfc/0x120 [ 32.729321] [] do_syscall_64+0x364/0x490 [ 32.735006] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 32.741906] 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 [ 32.769159] RIP [] l2tp_session_free+0x11c/0x200 [ 32.775672] RSP [ 32.779269] CR2: 0000000000000080 [ 32.782998] ---[ end trace e94d2eb3f05e9d34 ]--- [ 32.787851] Kernel panic - not syncing: Fatal exception [ 32.793899] Dumping ftrace buffer: [ 32.797610] (ftrace buffer empty) [ 32.801314] Kernel Offset: disabled [ 32.804922] Rebooting in 86400 seconds..