[....] 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[ 13.438492] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.015559] random: sshd: uninitialized urandom read (32 bytes read) [ 18.300538] random: sshd: uninitialized urandom read (32 bytes read) [ 18.813723] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.50' (ECDSA) to the list of known hosts. [ 24.459386] urandom_read: 1 callbacks suppressed [ 24.459389] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.642582] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.650835] IP: [] l2tp_session_free+0x11c/0x200 [ 24.657366] PGD 1c6a87067 [ 24.660011] PUD 1c6ae2067 PMD 0 [ 24.663545] [ 24.665172] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.669731] Dumping ftrace buffer: [ 24.673255] (ftrace buffer empty) [ 24.676945] Modules linked in: [ 24.680239] CPU: 0 PID: 3798 Comm: syz-executor753 Not tainted 4.9.122-g54068d6 #26 [ 24.688272] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.697613] task: ffff8801b6e68000 task.stack: ffff8801d9840000 [ 24.703642] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.712603] RSP: 0018:ffff8801d9847ca0 EFLAGS: 00010246 [ 24.718028] RAX: dffffc0000000000 RBX: ffff8801b6ee7180 RCX: 0000000000000000 [ 24.725282] RDX: 1ffff10036ddcf00 RSI: ffffffff836c39a1 RDI: ffff8801b6ee7800 [ 24.732691] RBP: ffff8801d9847cc0 R08: ffff8801b6e688e8 R09: 0000000000000000 [ 24.739942] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6ee7680 [ 24.747195] R13: ffff8801b6ee7188 R14: 0000000000000000 R15: ffffffff83019be0 [ 24.754445] FS: 00000000010a3880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 24.762645] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.768503] CR2: 0000000000000080 CR3: 00000001c6bea000 CR4: 00000000001606f0 [ 24.775758] Stack: [ 24.777896] ffff8801b6e5d500 ffff8801b6ee7180 ffff8801b6e5d8d0 ffff8801b6e5d7d8 [ 24.785964] ffff8801d9847ce8 ffffffff836cb2b2 ffff8801b6e5d940 ffff8801b6e5d500 [ 24.793978] ffffffff836cb1e0 ffff8801d9847d20 ffffffff830270f5 ffff8801b6e5d940 [ 24.801988] Call Trace: [ 24.804555] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.811205] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.817508] [] __sk_destruct+0x55/0x590 [ 24.823177] [] ? sock_release+0x1c0/0x1c0 [ 24.828960] [] sk_destruct+0x63/0x80 [ 24.834305] [] __sk_free+0x4f/0x220 [ 24.839562] [] sk_free+0x2b/0x40 [ 24.844559] [] pppol2tp_release+0x239/0x2e0 [ 24.850520] [] sock_release+0x96/0x1c0 [ 24.856038] [] sock_close+0x16/0x20 [ 24.861300] [] __fput+0x263/0x700 [ 24.866383] [] ____fput+0x15/0x20 [ 24.871467] [] task_work_run+0x10c/0x180 [ 24.877157] [] exit_to_usermode_loop+0xfc/0x120 [ 24.883531] [] do_syscall_64+0x364/0x490 [ 24.889229] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.896162] 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 [ 24.923398] RIP [] l2tp_session_free+0x11c/0x200 [ 24.930044] RSP [ 24.933647] CR2: 0000000000000080 [ 24.937444] ---[ end trace c141fc547a90ec8c ]--- [ 24.942200] Kernel panic - not syncing: Fatal exception [ 24.948012] Dumping ftrace buffer: [ 24.951535] (ftrace buffer empty) [ 24.955268] Kernel Offset: disabled [ 24.958883] Rebooting in 86400 seconds..