[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.451354] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.518778] random: sshd: uninitialized urandom read (32 bytes read) [ 20.061157] random: sshd: uninitialized urandom read (32 bytes read) [ 20.631648] random: sshd: uninitialized urandom read (32 bytes read) [ 20.773925] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.49' (ECDSA) to the list of known hosts. [ 26.411855] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.625908] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.634163] IP: [<ffffffff836c39cc>] l2tp_session_free+0x11c/0x200 [ 26.640584] PGD 1ca843067 [ 26.643242] PUD 1cab7b067 PMD 0 [ 26.646726] [ 26.648347] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.652865] Dumping ftrace buffer: [ 26.656382] (ftrace buffer empty) [ 26.660067] Modules linked in: [ 26.663380] CPU: 0 PID: 3722 Comm: syz-executor488 Not tainted 4.9.122-g54068d6 #78 [ 26.671149] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.680481] task: ffff8801c0349800 task.stack: ffff8801bf6b8000 [ 26.686509] RIP: 0010:[<ffffffff836c39cc>] [<ffffffff836c39cc>] l2tp_session_free+0x11c/0x200 [ 26.695366] RSP: 0018:ffff8801bf6bfca0 EFLAGS: 00010246 [ 26.700806] RAX: dffffc0000000000 RBX: ffff8801c0032c80 RCX: 0000000000000000 [ 26.708068] RDX: 1ffff10038091a60 RSI: ffffffff836c39a1 RDI: ffff8801c048d300 [ 26.715497] RBP: ffff8801bf6bfcc0 R08: ffff8801c034a0e8 R09: 0000000000000000 [ 26.722772] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c048d180 [ 26.730018] R13: ffff8801c0032c88 R14: 0000000000000000 R15: ffffffff83019be0 [ 26.737375] FS: 0000000000888880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 26.745773] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.751650] CR2: 0000000000000080 CR3: 00000001caabe000 CR4: 00000000001606f0 [ 26.758899] Stack: [ 26.761024] ffff8801c0e76e80 ffff8801c0032c80 ffff8801c0e77250 ffff8801c0e77158 [ 26.769210] ffff8801bf6bfce8 ffffffff836cb2b2 ffff8801c0e772c0 ffff8801c0e76e80 [ 26.777303] ffffffff836cb1e0 ffff8801bf6bfd20 ffffffff830270f5 ffff8801c0e772c0 [ 26.785317] Call Trace: [ 26.787900] [<ffffffff836cb2b2>] pppol2tp_session_destruct+0xd2/0x110 [ 26.794546] [<ffffffff836cb1e0>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.800889] [<ffffffff830270f5>] __sk_destruct+0x55/0x590 [ 26.806500] [<ffffffff83019be0>] ? sock_release+0x1c0/0x1c0 [ 26.812276] [<ffffffff8302eb83>] sk_destruct+0x63/0x80 [ 26.817637] [<ffffffff8302ebef>] __sk_free+0x4f/0x220 [ 26.822889] [<ffffffff8302edeb>] sk_free+0x2b/0x40 [ 26.827888] [<ffffffff836ce5b9>] pppol2tp_release+0x239/0x2e0 [ 26.833849] [<ffffffff83019ab6>] sock_release+0x96/0x1c0 [ 26.839381] [<ffffffff83019bf6>] sock_close+0x16/0x20 [ 26.844639] [<ffffffff8157bdd3>] __fput+0x263/0x700 [ 26.849721] [<ffffffff8157c2f5>] ____fput+0x15/0x20 [ 26.854803] [<ffffffff8119a62c>] task_work_run+0x10c/0x180 [ 26.860492] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 26.866795] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 26.872483] [<ffffffff83a00cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.879401] 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 <f0> 41 ff 8e 80 00 00 00 74 69 e8 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 26.906885] RIP [<ffffffff836c39cc>] l2tp_session_free+0x11c/0x200 [ 26.913452] RSP <ffff8801bf6bfca0> [ 26.917055] CR2: 0000000000000080 [ 26.920811] ---[ end trace f9fcc1c3f04e425d ]--- [ 26.925666] Kernel panic - not syncing: Fatal exception [ 26.931299] Dumping ftrace buffer: [ 26.934819] (ftrace buffer empty) [ 26.938506] Kernel Offset: disabled [ 26.942108] Rebooting in 86400 seconds..