[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.160474] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 33.882639] random: sshd: uninitialized urandom read (32 bytes read) [ 34.343913] random: sshd: uninitialized urandom read (32 bytes read) [ 35.025896] random: sshd: uninitialized urandom read (32 bytes read) [ 35.157822] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.47' (ECDSA) to the list of known hosts. [ 40.540575] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 40.735686] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 40.743922] IP: [] l2tp_session_free+0x11c/0x200 [ 40.750351] PGD 1d9599067 [ 40.752991] PUD 1d9598067 PMD 0 [ 40.756463] [ 40.758083] Oops: 0002 [#1] PREEMPT SMP KASAN [ 40.762551] Dumping ftrace buffer: [ 40.766063] (ftrace buffer empty) [ 40.769746] Modules linked in: [ 40.773028] CPU: 1 PID: 3810 Comm: syz-executor286 Not tainted 4.9.113-g90e7a90 #68 [ 40.780789] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 40.790115] task: ffff8801b6d0e000 task.stack: ffff8801d97c0000 [ 40.796141] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 40.804983] RSP: 0018:ffff8801d97c7ca0 EFLAGS: 00010246 [ 40.810413] RAX: dffffc0000000000 RBX: ffff8801b5879400 RCX: 0000000000000000 [ 40.817655] RDX: 1ffff10036be7030 RSI: ffffffff836bdee1 RDI: ffff8801b5f38180 [ 40.824900] RBP: ffff8801d97c7cc0 R08: ffff8801b6d0e8e8 R09: 0000000000000000 [ 40.832144] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5f38000 [ 40.839385] R13: ffff8801b5879408 R14: 0000000000000000 R15: ffffffff83014be0 [ 40.846630] FS: 0000000001136880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 40.854826] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 40.860676] CR2: 0000000000000080 CR3: 00000001d959a000 CR4: 00000000001606f0 [ 40.867920] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 40.875164] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 40.882404] Stack: [ 40.884526] ffff8801b5c06600 ffff8801b5879400 ffff8801b5c069d0 ffff8801b5c068d8 [ 40.892523] ffff8801d97c7ce8 ffffffff836c57f2 ffff8801b5c06a40 ffff8801b5c06600 [ 40.900507] ffffffff836c5720 ffff8801d97c7d20 ffffffff83022095 ffff8801b5c06a40 [ 40.908505] Call Trace: [ 40.911071] [] pppol2tp_session_destruct+0xd2/0x110 [ 40.917727] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 40.924021] [] __sk_destruct+0x55/0x590 [ 40.929615] [] ? sock_release+0x1c0/0x1c0 [ 40.935384] [] sk_destruct+0x63/0x80 [ 40.940720] [] __sk_free+0x4f/0x220 [ 40.945981] [] sk_free+0x2b/0x40 [ 40.950971] [] pppol2tp_release+0x239/0x2e0 [ 40.956918] [] sock_release+0x96/0x1c0 [ 40.962429] [] sock_close+0x16/0x20 [ 40.967682] [] __fput+0x263/0x700 [ 40.972757] [] ____fput+0x15/0x20 [ 40.977833] [] task_work_run+0x10c/0x180 [ 40.983517] [] exit_to_usermode_loop+0xfc/0x120 [ 40.989805] [] do_syscall_64+0x364/0x490 [ 40.995501] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 41.002405] 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 0b ca fd 4c 89 ea 48 b8 00 [ 41.029208] RIP [] l2tp_session_free+0x11c/0x200 [ 41.035709] RSP [ 41.039302] CR2: 0000000000000080 [ 41.042817] ---[ end trace 0bbec7f5f5e343f0 ]--- [ 41.047562] Kernel panic - not syncing: Fatal exception [ 41.053291] Dumping ftrace buffer: [ 41.056804] (ftrace buffer empty) [ 41.060490] Kernel Offset: disabled [ 41.064094] Rebooting in 86400 seconds..