[....] 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[ 13.245062] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.286445] random: sshd: uninitialized urandom read (32 bytes read) [ 18.609931] random: sshd: uninitialized urandom read (32 bytes read) [ 19.108934] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.59' (ECDSA) to the list of known hosts. [ 24.794036] urandom_read: 1 callbacks suppressed [ 24.794040] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.000664] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.008943] IP: [] l2tp_session_free+0x11c/0x200 [ 25.015370] PGD 1cad4a067 [ 25.018015] PUD 1c525f067 PMD 0 [ 25.021496] [ 25.023121] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.027604] Dumping ftrace buffer: [ 25.031128] (ftrace buffer empty) [ 25.034813] Modules linked in: [ 25.038107] CPU: 0 PID: 3699 Comm: syz-executor040 Not tainted 4.9.122-g54068d6 #78 [ 25.045870] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.055201] task: ffff8801c1c6c800 task.stack: ffff8801c0e48000 [ 25.061235] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.070099] RSP: 0018:ffff8801c0e4fca0 EFLAGS: 00010246 [ 25.075523] RAX: dffffc0000000000 RBX: ffff8801c1eeec80 RCX: 0000000000000000 [ 25.082767] RDX: 1ffff100383ac830 RSI: ffffffff836c39a1 RDI: ffff8801c1d64180 [ 25.090037] RBP: ffff8801c0e4fcc0 R08: ffff8801c1c6d0e8 R09: 0000000000000000 [ 25.097290] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c1d64000 [ 25.104538] R13: ffff8801c1eeec88 R14: 0000000000000000 R15: ffffffff83019be0 [ 25.111788] FS: 0000000001226880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 25.119989] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.125851] CR2: 0000000000000080 CR3: 00000001c36ac000 CR4: 00000000001606f0 [ 25.133096] Stack: [ 25.135226] ffff8801caa0c400 ffff8801c1eeec80 ffff8801caa0c7d0 ffff8801caa0c6d8 [ 25.143245] ffff8801c0e4fce8 ffffffff836cb2b2 ffff8801caa0c840 ffff8801caa0c400 [ 25.151356] ffffffff836cb1e0 ffff8801c0e4fd20 ffffffff830270f5 ffff8801caa0c840 [ 25.159351] Call Trace: [ 25.161920] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.168572] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.174879] [] __sk_destruct+0x55/0x590 [ 25.180506] [] ? sock_release+0x1c0/0x1c0 [ 25.186279] [] sk_destruct+0x63/0x80 [ 25.191618] [] __sk_free+0x4f/0x220 [ 25.196870] [] sk_free+0x2b/0x40 [ 25.201868] [] pppol2tp_release+0x239/0x2e0 [ 25.207820] [] sock_release+0x96/0x1c0 [ 25.213334] [] sock_close+0x16/0x20 [ 25.218637] [] __fput+0x263/0x700 [ 25.223728] [] ____fput+0x15/0x20 [ 25.228809] [] task_work_run+0x10c/0x180 [ 25.234566] [] exit_to_usermode_loop+0xfc/0x120 [ 25.240868] [] do_syscall_64+0x364/0x490 [ 25.246564] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.253461] 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 [ 25.280433] RIP [] l2tp_session_free+0x11c/0x200 [ 25.286952] RSP [ 25.290556] CR2: 0000000000000080 [ 25.294298] ---[ end trace 74e0a98984d7254e ]--- [ 25.299059] Kernel panic - not syncing: Fatal exception [ 25.304688] Dumping ftrace buffer: [ 25.308210] (ftrace buffer empty) [ 25.311896] Kernel Offset: disabled [ 25.315495] Rebooting in 86400 seconds..