[....] 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[ 15.951695] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 28.155607] random: sshd: uninitialized urandom read (32 bytes read) [ 28.594552] random: sshd: uninitialized urandom read (32 bytes read) [ 28.989091] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.39' (ECDSA) to the list of known hosts. [ 34.678191] urandom_read: 1 callbacks suppressed [ 34.678194] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.878773] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.887049] IP: [] l2tp_session_free+0x11c/0x200 [ 34.893644] PGD 1c5eb1067 [ 34.896314] PUD 1c7153067 PMD 0 [ 34.899792] [ 34.901421] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.905890] Dumping ftrace buffer: [ 34.909400] (ftrace buffer empty) [ 34.913095] Modules linked in: [ 34.916387] CPU: 0 PID: 3686 Comm: syz-executor947 Not tainted 4.9.122-g54068d6 #78 [ 34.924323] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.933730] task: ffff8801c2ab9800 task.stack: ffff8801c1c58000 [ 34.939767] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.948948] RSP: 0018:ffff8801c1c5fca0 EFLAGS: 00010246 [ 34.954559] RAX: dffffc0000000000 RBX: ffff8801c20a7900 RCX: 0000000000000000 [ 34.961810] RDX: 1ffff100384ee6b0 RSI: ffffffff836c39a1 RDI: ffff8801c2773580 [ 34.969059] RBP: ffff8801c1c5fcc0 R08: ffff8801c2aba0e8 R09: 0000000000000000 [ 34.976307] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c2773400 [ 34.983557] R13: ffff8801c20a7908 R14: 0000000000000000 R15: ffffffff83019be0 [ 34.990849] FS: 000000000261d880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 34.999059] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 35.004915] CR2: 0000000000000080 CR3: 00000001c5fb7000 CR4: 00000000001606f0 [ 35.012266] Stack: [ 35.014419] ffff8801c2479980 ffff8801c20a7900 ffff8801c2479d50 ffff8801c2479c58 [ 35.022421] ffff8801c1c5fce8 ffffffff836cb2b2 ffff8801c2479dc0 ffff8801c2479980 [ 35.030627] ffffffff836cb1e0 ffff8801c1c5fd20 ffffffff830270f5 ffff8801c2479dc0 [ 35.038690] Call Trace: [ 35.041262] [] pppol2tp_session_destruct+0xd2/0x110 [ 35.047914] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 35.054216] [] __sk_destruct+0x55/0x590 [ 35.059877] [] ? sock_release+0x1c0/0x1c0 [ 35.065663] [] sk_destruct+0x63/0x80 [ 35.071013] [] __sk_free+0x4f/0x220 [ 35.076269] [] sk_free+0x2b/0x40 [ 35.081267] [] pppol2tp_release+0x239/0x2e0 [ 35.087221] [] sock_release+0x96/0x1c0 [ 35.092877] [] sock_close+0x16/0x20 [ 35.098136] [] __fput+0x263/0x700 [ 35.103226] [] ____fput+0x15/0x20 [ 35.108313] [] task_work_run+0x10c/0x180 [ 35.114018] [] exit_to_usermode_loop+0xfc/0x120 [ 35.120314] [] do_syscall_64+0x364/0x490 [ 35.126009] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 35.132908] 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 [ 35.159912] RIP [] l2tp_session_free+0x11c/0x200 [ 35.166416] RSP [ 35.170017] CR2: 0000000000000080 [ 35.174044] ---[ end trace 01de6c25168516c4 ]--- [ 35.178811] Kernel panic - not syncing: Fatal exception [ 35.184485] Dumping ftrace buffer: [ 35.188006] (ftrace buffer empty) [ 35.191688] Kernel Offset: disabled [ 35.195292] Rebooting in 86400 seconds..