[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.118333] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.964278] random: sshd: uninitialized urandom read (32 bytes read) [ 27.343661] random: sshd: uninitialized urandom read (32 bytes read) [ 27.826623] random: sshd: uninitialized urandom read (32 bytes read) [ 41.339911] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.17' (ECDSA) to the list of known hosts. [ 46.885523] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 47.102509] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 47.110900] IP: [] l2tp_session_free+0x11c/0x200 [ 47.117319] PGD 1c3773067 [ 47.119959] PUD 1c3785067 PMD 0 [ 47.123442] [ 47.125065] Oops: 0002 [#1] PREEMPT SMP KASAN [ 47.129532] Dumping ftrace buffer: [ 47.133046] (ftrace buffer empty) [ 47.136733] Modules linked in: [ 47.140077] CPU: 0 PID: 3693 Comm: syz-executor652 Not tainted 4.9.123-g520d10d3 #29 [ 47.148035] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 47.157379] task: ffff8801c477c800 task.stack: ffff8801c2328000 [ 47.163425] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 47.172275] RSP: 0018:ffff8801c232fc98 EFLAGS: 00010246 [ 47.177698] RAX: dffffc0000000000 RBX: ffff8801c9ebe780 RCX: 0000000000000000 [ 47.185048] RDX: 1ffff10038602b00 RSI: ffffffff836c4a91 RDI: ffff8801c3015800 [ 47.192396] RBP: ffff8801c232fcb8 R08: ffff8801c477d0e8 R09: 0000000000000000 [ 47.199747] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c3015680 [ 47.206991] R13: ffff8801c9ebe788 R14: 0000000000000000 R15: 0000000000000000 [ 47.214300] FS: 000000000127f880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 47.222507] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 47.228373] CR2: 0000000000000080 CR3: 00000001c3260000 CR4: 00000000001606f0 [ 47.235620] Stack: [ 47.237769] ffff8801c2308880 ffff8801c9ebe780 ffff8801c2308c50 ffff8801c2308b58 [ 47.245777] ffff8801c232fce0 ffffffff836cc3a2 ffff8801c2308cc0 ffff8801c2308880 [ 47.253786] ffffffff836cc2d0 ffff8801c232fd18 ffffffff830281f5 ffff8801c2308cc0 [ 47.261888] Call Trace: [ 47.264460] [] pppol2tp_session_destruct+0xd2/0x110 [ 47.271291] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 47.277592] [] __sk_destruct+0x55/0x590 [ 47.283195] [] sk_destruct+0x63/0x80 [ 47.288560] [] __sk_free+0x4f/0x220 [ 47.293819] [] sk_free+0x2b/0x40 [ 47.298812] [] pppol2tp_release+0x239/0x2e0 [ 47.304763] [] __sock_release+0xd7/0x260 [ 47.310452] [] ? __sock_release+0x260/0x260 [ 47.316400] [] sock_close+0x19/0x20 [ 47.321653] [] __fput+0x263/0x700 [ 47.326731] [] ____fput+0x15/0x20 [ 47.331815] [] task_work_run+0x10c/0x180 [ 47.337506] [] exit_to_usermode_loop+0xfc/0x120 [ 47.343803] [] do_syscall_64+0x364/0x490 [ 47.349498] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 47.356410] 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 [ 47.383598] RIP [] l2tp_session_free+0x11c/0x200 [ 47.390210] RSP [ 47.393809] CR2: 0000000000000080 [ 47.398774] ---[ end trace 2bb566863804a2f1 ]--- [ 47.403534] Kernel panic - not syncing: Fatal exception [ 47.409187] Dumping ftrace buffer: [ 47.412705] (ftrace buffer empty) [ 47.416463] Kernel Offset: disabled [ 47.420069] Rebooting in 86400 seconds..