[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.465547] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.751819] random: sshd: uninitialized urandom read (32 bytes read) [ 16.274727] random: sshd: uninitialized urandom read (32 bytes read) [ 16.791417] random: sshd: uninitialized urandom read (32 bytes read) [ 16.938707] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.27' (ECDSA) to the list of known hosts. [ 22.512957] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 22.708642] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 22.716865] IP: [] l2tp_session_free+0x11c/0x200 [ 22.723315] PGD 1c5da6067 [ 22.725959] PUD 1c5e44067 PMD 0 [ 22.729445] [ 22.731068] Oops: 0002 [#1] PREEMPT SMP KASAN [ 22.735538] Dumping ftrace buffer: [ 22.739050] (ftrace buffer empty) [ 22.742734] Modules linked in: [ 22.746016] CPU: 1 PID: 3751 Comm: syz-executor074 Not tainted 4.9.122-g54068d6 #78 [ 22.753777] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 22.763126] task: ffff8801bd85c800 task.stack: ffff8801c3770000 [ 22.769155] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 22.778010] RSP: 0018:ffff8801c3777ca0 EFLAGS: 00010246 [ 22.783432] RAX: dffffc0000000000 RBX: ffff8801bdbc3900 RCX: 0000000000000000 [ 22.790685] RDX: 1ffff100378e4210 RSI: ffffffff836c39a1 RDI: ffff8801bc721080 [ 22.797932] RBP: ffff8801c3777cc0 R08: ffff8801bd85d0e8 R09: 0000000000000000 [ 22.805174] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bc720f00 [ 22.812418] R13: ffff8801bdbc3908 R14: 0000000000000000 R15: ffffffff83019be0 [ 22.819669] FS: 0000000001ab1880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 22.827865] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 22.833731] CR2: 0000000000000080 CR3: 00000001c14fb000 CR4: 00000000001606f0 [ 22.840978] Stack: [ 22.843098] ffff8801d55f3300 ffff8801bdbc3900 ffff8801d55f36d0 ffff8801d55f35d8 [ 22.851090] ffff8801c3777ce8 ffffffff836cb2b2 ffff8801d55f3740 ffff8801d55f3300 [ 22.859109] ffffffff836cb1e0 ffff8801c3777d20 ffffffff830270f5 ffff8801d55f3740 [ 22.867133] Call Trace: [ 22.869696] [] pppol2tp_session_destruct+0xd2/0x110 [ 22.876337] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 22.882632] [] __sk_destruct+0x55/0x590 [ 22.888229] [] ? sock_release+0x1c0/0x1c0 [ 22.894019] [] sk_destruct+0x63/0x80 [ 22.899358] [] __sk_free+0x4f/0x220 [ 22.904607] [] sk_free+0x2b/0x40 [ 22.909599] [] pppol2tp_release+0x239/0x2e0 [ 22.915574] [] sock_release+0x96/0x1c0 [ 22.921086] [] sock_close+0x16/0x20 [ 22.926338] [] __fput+0x263/0x700 [ 22.931414] [] ____fput+0x15/0x20 [ 22.936501] [] task_work_run+0x10c/0x180 [ 22.942191] [] exit_to_usermode_loop+0xfc/0x120 [ 22.948489] [] do_syscall_64+0x364/0x490 [ 22.954175] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 22.961100] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 22.988034] RIP [] l2tp_session_free+0x11c/0x200 [ 22.994538] RSP [ 22.998133] CR2: 0000000000000080 [ 23.001661] ---[ end trace ecfadf4cc28e7596 ]--- [ 23.006413] Kernel panic - not syncing: Fatal exception [ 23.012063] Dumping ftrace buffer: [ 23.015583] (ftrace buffer empty) [ 23.019267] Kernel Offset: disabled [ 23.022868] Rebooting in 86400 seconds..