[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.467986] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.879189] random: sshd: uninitialized urandom read (32 bytes read) [ 18.237166] random: sshd: uninitialized urandom read (32 bytes read) [ 19.227299] random: sshd: uninitialized urandom read (32 bytes read) [ 19.370490] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.22' (ECDSA) to the list of known hosts. [ 24.772474] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.965576] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.973811] IP: [] l2tp_session_free+0x11c/0x200 [ 24.980238] PGD 1c3068067 [ 24.982879] PUD 1c305f067 PMD 0 [ 24.986355] [ 24.987973] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.992438] Dumping ftrace buffer: [ 24.995960] (ftrace buffer empty) [ 24.999646] Modules linked in: [ 25.002946] CPU: 1 PID: 3750 Comm: syz-executor916 Not tainted 4.9.116-g0137ea2 #18 [ 25.010721] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.020062] task: ffff8801bddc9800 task.stack: ffff8801bbed8000 [ 25.026096] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.034942] RSP: 0018:ffff8801bbedfca0 EFLAGS: 00010246 [ 25.040375] RAX: dffffc0000000000 RBX: ffff8801bc307b80 RCX: 0000000000000000 [ 25.047619] RDX: 1ffff100378e40d0 RSI: ffffffff836be8f1 RDI: ffff8801bc720680 [ 25.054869] RBP: ffff8801bbedfcc0 R08: ffff8801bddca0e8 R09: 0000000000000000 [ 25.062115] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bc720500 [ 25.069360] R13: ffff8801bc307b88 R14: 0000000000000000 R15: ffffffff83014be0 [ 25.076608] FS: 000000000252a880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 25.084809] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.090662] CR2: 0000000000000080 CR3: 00000001c6bca000 CR4: 00000000001606f0 [ 25.097908] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.105164] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.112405] Stack: [ 25.114527] ffff8801bbd24400 ffff8801bc307b80 ffff8801bbd247d0 ffff8801bbd246d8 [ 25.122529] ffff8801bbedfce8 ffffffff836c6202 ffff8801bbd24840 ffff8801bbd24400 [ 25.130521] ffffffff836c6130 ffff8801bbedfd20 ffffffff83022095 ffff8801bbd24840 [ 25.138507] Call Trace: [ 25.141073] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.147722] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.154014] [] __sk_destruct+0x55/0x590 [ 25.159612] [] ? sock_release+0x1c0/0x1c0 [ 25.165382] [] sk_destruct+0x63/0x80 [ 25.170718] [] __sk_free+0x4f/0x220 [ 25.175966] [] sk_free+0x2b/0x40 [ 25.180956] [] pppol2tp_release+0x239/0x2e0 [ 25.186903] [] sock_release+0x96/0x1c0 [ 25.192423] [] sock_close+0x16/0x20 [ 25.197675] [] __fput+0x263/0x700 [ 25.202751] [] ____fput+0x15/0x20 [ 25.207830] [] task_work_run+0x10c/0x180 [ 25.213517] [] exit_to_usermode_loop+0xfc/0x120 [ 25.219806] [] do_syscall_64+0x364/0x490 [ 25.225499] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.232413] 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 [ 25.259336] RIP [] l2tp_session_free+0x11c/0x200 [ 25.265848] RSP [ 25.269444] CR2: 0000000000000080 [ 25.272947] ---[ end trace bc65cfad76804814 ]--- [ 25.277710] Kernel panic - not syncing: Fatal exception [ 25.283379] Dumping ftrace buffer: [ 25.286907] (ftrace buffer empty) [ 25.290594] Kernel Offset: disabled [ 25.294213] Rebooting in 86400 seconds..