[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.946822] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.889810] random: sshd: uninitialized urandom read (32 bytes read) [ 17.051388] random: sshd: uninitialized urandom read (32 bytes read) [ 17.550129] random: sshd: uninitialized urandom read (32 bytes read) [ 21.372532] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.60' (ECDSA) to the list of known hosts. [ 26.784534] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.979811] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.988108] IP: [] l2tp_session_free+0x11c/0x200 [ 26.994529] PGD 1c45d9067 [ 26.997182] PUD 1c1848067 PMD 0 [ 27.000660] [ 27.002277] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.006746] Dumping ftrace buffer: [ 27.010258] (ftrace buffer empty) [ 27.013939] Modules linked in: [ 27.017226] CPU: 1 PID: 3736 Comm: syz-executor626 Not tainted 4.9.119-g9dc978d #75 [ 27.024990] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.034368] task: ffff8801bf606000 task.stack: ffff8801be1e8000 [ 27.040408] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.049309] RSP: 0018:ffff8801be1efca0 EFLAGS: 00010246 [ 27.054728] RAX: dffffc0000000000 RBX: ffff8801be79db80 RCX: 0000000000000000 [ 27.061973] RDX: 1ffff1003964d1c0 RSI: ffffffff836bf9a1 RDI: ffff8801cb268e00 [ 27.069286] RBP: ffff8801be1efcc0 R08: ffff8801bf6068e8 R09: 0000000000000000 [ 27.076537] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb268c80 [ 27.083781] R13: ffff8801be79db88 R14: 0000000000000000 R15: ffffffff83015be0 [ 27.091023] FS: 000000000072b880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 27.099219] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.105085] CR2: 0000000000000080 CR3: 00000001c6d2e000 CR4: 00000000001606f0 [ 27.112335] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.119585] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.126830] Stack: [ 27.128955] ffff8801be109980 ffff8801be79db80 ffff8801be109d50 ffff8801be109c58 [ 27.136939] ffff8801be1efce8 ffffffff836c72b2 ffff8801be109dc0 ffff8801be109980 [ 27.144924] ffffffff836c71e0 ffff8801be1efd20 ffffffff830230f5 ffff8801be109dc0 [ 27.152957] Call Trace: [ 27.155531] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.162177] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.168594] [] __sk_destruct+0x55/0x590 [ 27.174194] [] ? sock_release+0x1c0/0x1c0 [ 27.180011] [] sk_destruct+0x63/0x80 [ 27.185420] [] __sk_free+0x4f/0x220 [ 27.190676] [] sk_free+0x2b/0x40 [ 27.195664] [] pppol2tp_release+0x239/0x2e0 [ 27.201609] [] sock_release+0x96/0x1c0 [ 27.207117] [] sock_close+0x16/0x20 [ 27.212367] [] __fput+0x263/0x700 [ 27.217447] [] ____fput+0x15/0x20 [ 27.222526] [] task_work_run+0x10c/0x180 [ 27.228324] [] exit_to_usermode_loop+0xfc/0x120 [ 27.234628] [] do_syscall_64+0x364/0x490 [ 27.240321] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.247216] 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 f5 f0 c9 fd 4c 89 ea 48 b8 00 [ 27.274297] RIP [] l2tp_session_free+0x11c/0x200 [ 27.280878] RSP [ 27.284486] CR2: 0000000000000080 [ 27.289347] ---[ end trace 53ceade20fd99ca6 ]--- [ 27.294225] Kernel panic - not syncing: Fatal exception [ 27.299889] Dumping ftrace buffer: [ 27.303401] (ftrace buffer empty) [ 27.307092] Kernel Offset: disabled [ 27.310741] Rebooting in 86400 seconds..