[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.265984] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.556499] random: sshd: uninitialized urandom read (32 bytes read) [ 18.792401] random: sshd: uninitialized urandom read (32 bytes read) [ 19.325485] random: sshd: uninitialized urandom read (32 bytes read) [ 35.188359] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.61' (ECDSA) to the list of known hosts. [ 40.797215] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 41.015588] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 41.024143] IP: [] l2tp_session_free+0x11c/0x200 [ 41.031136] PGD 1be37e067 [ 41.033800] PUD 1be32c067 PMD 0 [ 41.037404] [ 41.039040] Oops: 0002 [#1] PREEMPT SMP KASAN [ 41.043520] Dumping ftrace buffer: [ 41.047173] (ftrace buffer empty) [ 41.050875] Modules linked in: [ 41.054192] CPU: 1 PID: 3796 Comm: syz-executor060 Not tainted 4.9.122-g54068d6 #26 [ 41.061971] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 41.071763] task: ffff8801bb9ac800 task.stack: ffff8801d98b0000 [ 41.078298] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 41.087175] RSP: 0018:ffff8801d98b7ca0 EFLAGS: 00010246 [ 41.092614] RAX: dffffc0000000000 RBX: ffff8801c8ce1680 RCX: 0000000000000000 [ 41.100018] RDX: 1ffff100371d6b00 RSI: ffffffff836c39a1 RDI: ffff8801b8eb5800 [ 41.107431] RBP: ffff8801d98b7cc0 R08: ffff8801bb9ad0e8 R09: 0000000000000000 [ 41.114703] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b8eb5680 [ 41.121967] R13: ffff8801c8ce1688 R14: 0000000000000000 R15: ffffffff83019be0 [ 41.129242] FS: 0000000002034880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 41.137472] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 41.143342] CR2: 0000000000000080 CR3: 00000001c32df000 CR4: 00000000001606f0 [ 41.150609] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 41.157873] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 41.165130] Stack: [ 41.167277] ffff8801c72ac400 ffff8801c8ce1680 ffff8801c72ac7d0 ffff8801c72ac6d8 [ 41.176000] ffff8801d98b7ce8 ffffffff836cb2b2 ffff8801c72ac840 ffff8801c72ac400 [ 41.184034] ffffffff836cb1e0 ffff8801d98b7d20 ffffffff830270f5 ffff8801c72ac840 [ 41.192065] Call Trace: [ 41.194646] [] pppol2tp_session_destruct+0xd2/0x110 [ 41.201316] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 41.207678] [] __sk_destruct+0x55/0x590 [ 41.213306] [] ? sock_release+0x1c0/0x1c0 [ 41.219098] [] sk_destruct+0x63/0x80 [ 41.224459] [] __sk_free+0x4f/0x220 [ 41.229727] [] sk_free+0x2b/0x40 [ 41.234739] [] pppol2tp_release+0x239/0x2e0 [ 41.240710] [] sock_release+0x96/0x1c0 [ 41.246259] [] sock_close+0x16/0x20 [ 41.251533] [] __fput+0x263/0x700 [ 41.256937] [] ____fput+0x15/0x20 [ 41.262344] [] task_work_run+0x10c/0x180 [ 41.268056] [] exit_to_usermode_loop+0xfc/0x120 [ 41.274489] [] do_syscall_64+0x364/0x490 [ 41.280336] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 41.287249] 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 [ 41.314333] RIP [] l2tp_session_free+0x11c/0x200 [ 41.320861] RSP [ 41.324465] CR2: 0000000000000080 [ 41.328301] ---[ end trace 11394f5b566afd3d ]--- [ 41.333067] Kernel panic - not syncing: Fatal exception [ 41.338792] Dumping ftrace buffer: [ 41.342324] (ftrace buffer empty) [ 41.346026] Kernel Offset: disabled [ 41.349654] Rebooting in 86400 seconds..