[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.435638] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.544063] random: sshd: uninitialized urandom read (32 bytes read) [ 18.924986] random: sshd: uninitialized urandom read (32 bytes read) [ 19.435940] random: sshd: uninitialized urandom read (32 bytes read) [ 26.041602] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.57' (ECDSA) to the list of known hosts. [ 31.559531] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 31.777185] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 31.785667] IP: [] l2tp_session_free+0x11c/0x200 [ 31.792096] PGD 1c5b98067 [ 31.794744] PUD 1c76a3067 PMD 0 [ 31.798225] [ 31.799853] Oops: 0002 [#1] PREEMPT SMP KASAN [ 31.804328] Dumping ftrace buffer: [ 31.807842] (ftrace buffer empty) [ 31.811531] Modules linked in: [ 31.814832] CPU: 1 PID: 3764 Comm: syz-executor431 Not tainted 4.9.124-g09eb2ba #83 [ 31.822710] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.832055] task: ffff8801bdb6e000 task.stack: ffff8801be6b0000 [ 31.838145] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 31.847013] RSP: 0018:ffff8801be6b7c98 EFLAGS: 00010246 [ 31.852448] RAX: dffffc0000000000 RBX: ffff8801bc31a500 RCX: 0000000000000000 [ 31.859694] RDX: 1ffff1003778af00 RSI: ffffffff836c4711 RDI: ffff8801bbc57800 [ 31.866942] RBP: ffff8801be6b7cb8 R08: ffff8801bdb6e8e8 R09: 0000000000000000 [ 31.874193] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bbc57680 [ 31.881443] R13: ffff8801bc31a508 R14: 0000000000000000 R15: 0000000000000000 [ 31.888692] FS: 0000000001be5880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 31.896894] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 31.902755] CR2: 0000000000000080 CR3: 00000001bdb87000 CR4: 00000000001606f0 [ 31.910002] Stack: [ 31.912130] ffff8801beb80880 ffff8801bc31a500 ffff8801beb80c50 ffff8801beb80b58 [ 31.920219] ffff8801be6b7ce0 ffffffff836cc022 ffff8801beb80cc0 ffff8801beb80880 [ 31.928271] ffffffff836cbf50 ffff8801be6b7d18 ffffffff830281f5 ffff8801beb80cc0 [ 31.936275] Call Trace: [ 31.938851] [] pppol2tp_session_destruct+0xd2/0x110 [ 31.945506] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 31.951807] [] __sk_destruct+0x55/0x590 [ 31.957411] [] sk_destruct+0x63/0x80 [ 31.962754] [] __sk_free+0x4f/0x220 [ 31.968008] [] sk_free+0x2b/0x40 [ 31.973010] [] pppol2tp_release+0x239/0x2e0 [ 31.978965] [] __sock_release+0xd7/0x260 [ 31.984652] [] ? __sock_release+0x260/0x260 [ 31.990599] [] sock_close+0x19/0x20 [ 31.995852] [] __fput+0x263/0x700 [ 32.000932] [] ____fput+0x15/0x20 [ 32.006015] [] task_work_run+0x10c/0x180 [ 32.011712] [] exit_to_usermode_loop+0xfc/0x120 [ 32.018016] [] do_syscall_64+0x364/0x490 [ 32.023718] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 32.030627] 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 a5 c5 c9 fd 4c 89 ea 48 b8 00 [ 32.057781] RIP [] l2tp_session_free+0x11c/0x200 [ 32.064350] RSP [ 32.067950] CR2: 0000000000000080 [ 32.071947] ---[ end trace f88848b2983dba0d ]--- [ 32.076696] Kernel panic - not syncing: Fatal exception [ 32.082370] Dumping ftrace buffer: [ 32.085892] (ftrace buffer empty) [ 32.089578] Kernel Offset: disabled [ 32.093239] Rebooting in 86400 seconds..