[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.885191] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.198454] random: sshd: uninitialized urandom read (32 bytes read) [ 17.557876] random: sshd: uninitialized urandom read (32 bytes read) [ 17.997485] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.24' (ECDSA) to the list of known hosts. [ 23.602576] urandom_read: 1 callbacks suppressed [ 23.602580] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.804159] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.812386] IP: [] l2tp_session_free+0x11c/0x200 [ 23.818812] PGD 1cc58b067 [ 23.821454] PUD 1ca668067 PMD 0 [ 23.824987] [ 23.826617] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.831086] Dumping ftrace buffer: [ 23.834599] (ftrace buffer empty) [ 23.838283] Modules linked in: [ 23.841577] CPU: 0 PID: 3805 Comm: syz-executor433 Not tainted 4.9.118-g47b77b8 #72 [ 23.849345] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.858679] task: ffff8801b93ce000 task.stack: ffff8801b8348000 [ 23.864709] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.873564] RSP: 0018:ffff8801b834fca0 EFLAGS: 00010246 [ 23.878984] RAX: dffffc0000000000 RBX: ffff8801b5b4ac80 RCX: 0000000000000000 [ 23.886229] RDX: 1ffff10036b37e10 RSI: ffffffff836bf781 RDI: ffff8801b59bf080 [ 23.893479] RBP: ffff8801b834fcc0 R08: ffff8801b93ce8e8 R09: 0000000000000000 [ 23.900720] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b59bef00 [ 23.907967] R13: ffff8801b5b4ac88 R14: 0000000000000000 R15: ffffffff83015be0 [ 23.915213] FS: 0000000000ee9880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 23.923411] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.929371] CR2: 0000000000000080 CR3: 00000001c7047000 CR4: 00000000001606f0 [ 23.936625] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.943871] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.951113] Stack: [ 23.953235] ffff8801b5fcf700 ffff8801b5b4ac80 ffff8801b5fcfad0 ffff8801b5fcf9d8 [ 23.961225] ffff8801b834fce8 ffffffff836c7092 ffff8801b5fcfb40 ffff8801b5fcf700 [ 23.969262] ffffffff836c6fc0 ffff8801b834fd20 ffffffff830230f5 ffff8801b5fcfb40 [ 23.977259] Call Trace: [ 23.979825] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.986463] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.992753] [] __sk_destruct+0x55/0x590 [ 23.998352] [] ? sock_release+0x1c0/0x1c0 [ 24.004218] [] sk_destruct+0x63/0x80 [ 24.009568] [] __sk_free+0x4f/0x220 [ 24.014822] [] sk_free+0x2b/0x40 [ 24.019812] [] pppol2tp_release+0x239/0x2e0 [ 24.025778] [] sock_release+0x96/0x1c0 [ 24.031345] [] sock_close+0x16/0x20 [ 24.036604] [] __fput+0x263/0x700 [ 24.041681] [] ____fput+0x15/0x20 [ 24.046760] [] task_work_run+0x10c/0x180 [ 24.052531] [] exit_to_usermode_loop+0xfc/0x120 [ 24.058830] [] do_syscall_64+0x364/0x490 [ 24.064520] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.071416] 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 f5 f2 c9 fd 4c 89 ea 48 b8 00 [ 24.098417] RIP [] l2tp_session_free+0x11c/0x200 [ 24.104920] RSP [ 24.108522] CR2: 0000000000000080 [ 24.112294] ---[ end trace 208fce67b7184090 ]--- [ 24.117065] Kernel panic - not syncing: Fatal exception [ 24.122867] Dumping ftrace buffer: [ 24.126387] (ftrace buffer empty) [ 24.130077] Kernel Offset: disabled [ 24.133676] Rebooting in 86400 seconds..