[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.856465] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.048909] random: sshd: uninitialized urandom read (32 bytes read) [ 26.486988] random: sshd: uninitialized urandom read (32 bytes read) [ 26.999474] random: sshd: uninitialized urandom read (32 bytes read) [ 27.140965] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.195' (ECDSA) to the list of known hosts. [ 32.720849] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 32.929350] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 32.937599] IP: [] l2tp_session_free+0x11c/0x200 [ 32.944225] PGD 1c9711067 [ 32.946877] PUD 1c961a067 PMD 0 [ 32.950395] [ 32.952013] Oops: 0002 [#1] PREEMPT SMP KASAN [ 32.956579] Dumping ftrace buffer: [ 32.960093] (ftrace buffer empty) [ 32.963987] Modules linked in: [ 32.967292] CPU: 1 PID: 3806 Comm: syz-executor401 Not tainted 4.9.122-g54068d6 #26 [ 32.975061] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 32.984392] task: ffff8801b7379800 task.stack: ffff8801cb898000 [ 32.990426] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 32.999276] RSP: 0018:ffff8801cb89fca0 EFLAGS: 00010246 [ 33.004813] RAX: dffffc0000000000 RBX: ffff8801b5f24780 RCX: 0000000000000000 [ 33.012102] RDX: 1ffff10036dc6fa0 RSI: ffffffff836c39a1 RDI: ffff8801b6e37d00 [ 33.019473] RBP: ffff8801cb89fcc0 R08: ffff8801b737a0e8 R09: 0000000000000000 [ 33.026724] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6e37b80 [ 33.034017] R13: ffff8801b5f24788 R14: 0000000000000000 R15: ffffffff83019be0 [ 33.041276] FS: 00000000018ec880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 33.049481] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 33.055419] CR2: 0000000000000080 CR3: 00000001c75fb000 CR4: 00000000001606f0 [ 33.062672] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 33.069916] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 33.077158] Stack: [ 33.079326] ffff8801b6ee8880 ffff8801b5f24780 ffff8801b6ee8c50 ffff8801b6ee8b58 [ 33.087325] ffff8801cb89fce8 ffffffff836cb2b2 ffff8801b6ee8cc0 ffff8801b6ee8880 [ 33.095385] ffffffff836cb1e0 ffff8801cb89fd20 ffffffff830270f5 ffff8801b6ee8cc0 [ 33.103391] Call Trace: [ 33.105959] [] pppol2tp_session_destruct+0xd2/0x110 [ 33.112758] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 33.119103] [] __sk_destruct+0x55/0x590 [ 33.124708] [] ? sock_release+0x1c0/0x1c0 [ 33.130485] [] sk_destruct+0x63/0x80 [ 33.135822] [] __sk_free+0x4f/0x220 [ 33.141171] [] sk_free+0x2b/0x40 [ 33.146169] [] pppol2tp_release+0x239/0x2e0 [ 33.152236] [] sock_release+0x96/0x1c0 [ 33.157763] [] sock_close+0x16/0x20 [ 33.163022] [] __fput+0x263/0x700 [ 33.168110] [] ____fput+0x15/0x20 [ 33.173195] [] task_work_run+0x10c/0x180 [ 33.178974] [] exit_to_usermode_loop+0xfc/0x120 [ 33.185351] [] do_syscall_64+0x364/0x490 [ 33.191095] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 33.197995] 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 [ 33.225191] RIP [] l2tp_session_free+0x11c/0x200 [ 33.231688] RSP [ 33.235285] CR2: 0000000000000080 [ 33.238880] ---[ end trace 89f91568cf8b99ba ]--- [ 33.243655] Kernel panic - not syncing: Fatal exception [ 33.249330] Dumping ftrace buffer: [ 33.252849] (ftrace buffer empty) [ 33.256538] Kernel Offset: disabled [ 33.260139] Rebooting in 86400 seconds..