[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.317808] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 25.109548] random: sshd: uninitialized urandom read (32 bytes read) [ 25.530725] random: sshd: uninitialized urandom read (32 bytes read) [ 26.099839] random: sshd: uninitialized urandom read (32 bytes read) [ 26.464454] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.203' (ECDSA) to the list of known hosts. [ 32.160448] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 32.362132] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 32.370359] IP: [] l2tp_session_free+0x11c/0x200 [ 32.376792] PGD 1c2a1a067 [ 32.379435] PUD 1c2925067 PMD 0 [ 32.382906] [ 32.384527] Oops: 0002 [#1] PREEMPT SMP KASAN [ 32.389103] Dumping ftrace buffer: [ 32.392624] (ftrace buffer empty) [ 32.396307] Modules linked in: [ 32.399597] CPU: 0 PID: 3803 Comm: syz-executor464 Not tainted 4.9.121-g681e57b #25 [ 32.407361] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 32.416688] task: ffff8801b7f5e000 task.stack: ffff8801d9250000 [ 32.422715] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 32.431559] RSP: 0018:ffff8801d9257ca0 EFLAGS: 00010246 [ 32.436976] RAX: dffffc0000000000 RBX: ffff8801d986c280 RCX: 0000000000000000 [ 32.444219] RDX: 1ffff10036fc58d0 RSI: ffffffff836c29a1 RDI: ffff8801b7e2c680 [ 32.451463] RBP: ffff8801d9257cc0 R08: ffff8801b7f5e8e8 R09: 0000000000000000 [ 32.458714] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b7e2c500 [ 32.465961] R13: ffff8801d986c288 R14: 0000000000000000 R15: ffffffff83018be0 [ 32.473206] FS: 00000000008b6880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 32.481466] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 32.487328] CR2: 0000000000000080 CR3: 00000001bde88000 CR4: 00000000001606f0 [ 32.494577] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 32.501819] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 32.509058] Stack: [ 32.511179] ffff8801da3b1100 ffff8801d986c280 ffff8801da3b14d0 ffff8801da3b13d8 [ 32.519269] ffff8801d9257ce8 ffffffff836ca2b2 ffff8801da3b1540 ffff8801da3b1100 [ 32.522198] ffffffff836ca1e0 [ 32.522200] ffff8801d9257d20 ffffffff830260f5 ffff8801da3b1540[ 32.522204] Call Trace: [ 32.522215] [] pppol2tp_session_destruct+0xd2/0x110 [ 32.522220] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 32.522225] [] __sk_destruct+0x55/0x590 [ 32.522231] [] ? sock_release+0x1c0/0x1c0 [ 32.522235] [] sk_destruct+0x63/0x80 [ 32.522239] [] __sk_free+0x4f/0x220 [ 32.522243] [] sk_free+0x2b/0x40 [ 32.522247] [] pppol2tp_release+0x239/0x2e0 [ 32.522251] [] sock_release+0x96/0x1c0 [ 32.522255] [] sock_close+0x16/0x20 [ 32.522261] [] __fput+0x263/0x700 [ 32.522265] [] ____fput+0x15/0x20 [ 32.522286] [] task_work_run+0x10c/0x180 [ 32.522291] [] exit_to_usermode_loop+0xfc/0x120 [ 32.522295] [] do_syscall_64+0x364/0x490 [ 32.522301] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 32.522409] 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 65 df c9 fd 4c 89 ea 48 b8 00 [ 32.522414] RIP [] l2tp_session_free+0x11c/0x200 [ 32.522415] RSP [ 32.522417] CR2: 0000000000000080 [ 32.523647] ---[ end trace 1f94cce719f2c325 ]--- [ 32.523650] Kernel panic - not syncing: Fatal exception [ 32.527287] Dumping ftrace buffer: [ 32.527290] (ftrace buffer empty) [ 32.527291] Kernel Offset: disabled [ 32.683847] Rebooting in 86400 seconds..