[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.831313] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.304775] random: sshd: uninitialized urandom read (32 bytes read) [ 20.714745] random: sshd: uninitialized urandom read (32 bytes read) [ 21.218899] random: sshd: uninitialized urandom read (32 bytes read) [ 21.369243] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.44' (ECDSA) to the list of known hosts. [ 27.025991] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.226327] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.234558] IP: [] l2tp_session_free+0x11c/0x200 [ 27.240985] PGD 1bca35067 [ 27.243628] PUD 1bec31067 PMD 0 [ 27.247164] [ 27.248788] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.253261] Dumping ftrace buffer: [ 27.256783] (ftrace buffer empty) [ 27.260469] Modules linked in: [ 27.263753] CPU: 0 PID: 3761 Comm: syz-executor395 Not tainted 4.9.123-g520d10d3 #29 [ 27.271604] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.280932] task: ffff8801be649800 task.stack: ffff8801bbce0000 [ 27.286961] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.295839] RSP: 0018:ffff8801bbce7c98 EFLAGS: 00010246 [ 27.301266] RAX: dffffc0000000000 RBX: ffff8801c9094500 RCX: 0000000000000000 [ 27.308511] RDX: 1ffff10039270b50 RSI: ffffffff836c4a91 RDI: ffff8801c9385a80 [ 27.315757] RBP: ffff8801bbce7cb8 R08: ffff8801be64a0e8 R09: 0000000000000000 [ 27.323002] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9385900 [ 27.330246] R13: ffff8801c9094508 R14: 0000000000000000 R15: 0000000000000000 [ 27.337490] FS: 00000000008f9880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 27.345696] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.351557] CR2: 0000000000000080 CR3: 00000001be5b8000 CR4: 00000000001606f0 [ 27.358803] Stack: [ 27.360928] ffff8801bcf17700 ffff8801c9094500 ffff8801bcf17ad0 ffff8801bcf179d8 [ 27.368916] ffff8801bbce7ce0 ffffffff836cc3a2 ffff8801bcf17b40 ffff8801bcf17700 [ 27.376903] ffffffff836cc2d0 ffff8801bbce7d18 ffffffff830281f5 ffff8801bcf17b40 [ 27.384894] Call Trace: [ 27.387459] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.394118] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.400417] [] __sk_destruct+0x55/0x590 [ 27.406021] [] sk_destruct+0x63/0x80 [ 27.411372] [] __sk_free+0x4f/0x220 [ 27.416625] [] sk_free+0x2b/0x40 [ 27.421617] [] pppol2tp_release+0x239/0x2e0 [ 27.427564] [] __sock_release+0xd7/0x260 [ 27.433252] [] ? __sock_release+0x260/0x260 [ 27.439206] [] sock_close+0x19/0x20 [ 27.444459] [] __fput+0x263/0x700 [ 27.449539] [] ____fput+0x15/0x20 [ 27.454616] [] task_work_run+0x10c/0x180 [ 27.460367] [] exit_to_usermode_loop+0xfc/0x120 [ 27.466669] [] do_syscall_64+0x364/0x490 [ 27.472360] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.479259] 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 e5 c2 c9 fd 4c 89 ea 48 b8 00 [ 27.506186] RIP [] l2tp_session_free+0x11c/0x200 [ 27.512702] RSP [ 27.516306] CR2: 0000000000000080 [ 27.520324] ---[ end trace 8b678bfb3c3cc4a2 ]--- [ 27.525077] Kernel panic - not syncing: Fatal exception [ 27.530728] Dumping ftrace buffer: [ 27.534251] (ftrace buffer empty) [ 27.537937] Kernel Offset: disabled [ 27.541537] Rebooting in 86400 seconds..