[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.193380] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.192375] random: sshd: uninitialized urandom read (32 bytes read) [ 18.634290] random: sshd: uninitialized urandom read (32 bytes read) [ 19.654480] random: sshd: uninitialized urandom read (32 bytes read) [ 19.789539] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.6' (ECDSA) to the list of known hosts. [ 25.347609] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.542165] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.550391] IP: [] l2tp_session_free+0x11c/0x200 [ 25.556830] PGD 1c3e35067 [ 25.559495] PUD 1c239e067 PMD 0 [ 25.562965] [ 25.564594] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.569063] Dumping ftrace buffer: [ 25.572576] (ftrace buffer empty) [ 25.576260] Modules linked in: [ 25.579578] CPU: 0 PID: 3771 Comm: syz-executor777 Not tainted 4.9.116-g0137ea2 #18 [ 25.587343] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.596673] task: ffff8801bc720000 task.stack: ffff8801d9608000 [ 25.602719] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.611622] RSP: 0018:ffff8801d960fca0 EFLAGS: 00010246 [ 25.617042] RAX: dffffc0000000000 RBX: ffff8801da33b680 RCX: 0000000000000000 [ 25.624290] RDX: 1ffff1003922c880 RSI: ffffffff836be8f1 RDI: ffff8801c9164400 [ 25.631530] RBP: ffff8801d960fcc0 R08: ffff8801bc7208e8 R09: 0000000000000000 [ 25.638771] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9164280 [ 25.646014] R13: ffff8801da33b688 R14: 0000000000000000 R15: ffffffff83014be0 [ 25.653257] FS: 0000000000f02880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 25.661493] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.667348] CR2: 0000000000000080 CR3: 00000001c31e9000 CR4: 00000000001606f0 [ 25.674605] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.681861] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.689104] Stack: [ 25.691226] ffff8801bbab6600 ffff8801da33b680 ffff8801bbab69d0 ffff8801bbab68d8 [ 25.699260] ffff8801d960fce8 ffffffff836c6202 ffff8801bbab6a40 ffff8801bbab6600 [ 25.707268] ffffffff836c6130 ffff8801d960fd20 ffffffff83022095 ffff8801bbab6a40 [ 25.715250] Call Trace: [ 25.717812] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.724453] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.730768] [] __sk_destruct+0x55/0x590 [ 25.736381] [] ? sock_release+0x1c0/0x1c0 [ 25.742160] [] sk_destruct+0x63/0x80 [ 25.747497] [] __sk_free+0x4f/0x220 [ 25.752760] [] sk_free+0x2b/0x40 [ 25.757752] [] pppol2tp_release+0x239/0x2e0 [ 25.763698] [] sock_release+0x96/0x1c0 [ 25.769225] [] sock_close+0x16/0x20 [ 25.774477] [] __fput+0x263/0x700 [ 25.779559] [] ____fput+0x15/0x20 [ 25.784640] [] task_work_run+0x10c/0x180 [ 25.790325] [] exit_to_usermode_loop+0xfc/0x120 [ 25.796616] [] do_syscall_64+0x364/0x490 [ 25.802302] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.809211] 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 [ 25.836140] RIP [] l2tp_session_free+0x11c/0x200 [ 25.842651] RSP [ 25.846248] CR2: 0000000000000080 [ 25.849805] ---[ end trace c286f8b78f2c62a3 ]--- [ 25.854574] Kernel panic - not syncing: Fatal exception [ 25.860242] Dumping ftrace buffer: [ 25.863763] (ftrace buffer empty) [ 25.867478] Kernel Offset: disabled [ 25.871080] Rebooting in 86400 seconds..