[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.037732] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.743009] random: sshd: uninitialized urandom read (32 bytes read) [ 20.000163] random: sshd: uninitialized urandom read (32 bytes read) [ 20.486144] random: sshd: uninitialized urandom read (32 bytes read) [ 49.270709] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.50' (ECDSA) to the list of known hosts. [ 54.926669] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 55.123290] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 55.131519] IP: [] l2tp_session_free+0x11c/0x200 [ 55.137937] PGD 1c9a8b067 [ 55.140577] PUD 1c633a067 PMD 0 [ 55.144175] [ 55.145796] Oops: 0002 [#1] PREEMPT SMP KASAN [ 55.150264] Dumping ftrace buffer: [ 55.153820] (ftrace buffer empty) [ 55.157510] Modules linked in: [ 55.160795] CPU: 1 PID: 3821 Comm: syz-executor049 Not tainted 4.9.124-g09eb2ba #31 [ 55.168563] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 55.177899] task: ffff8801c3d2c800 task.stack: ffff8801d9488000 [ 55.183964] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 55.183967] RSP: 0018:ffff8801d948fc98 EFLAGS: 00010246 [ 55.183970] RAX: dffffc0000000000 RBX: ffff8801b6f2b180 RCX: 0000000000000000 [ 55.183972] RDX: 1ffff100395050d0 RSI: ffffffff836c4711 RDI: ffff8801ca828680 [ 55.183975] RBP: ffff8801d948fcb8 R08: ffff8801c3d2d0e8 R09: 0000000000000000 [ 55.183977] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ca828500 [ 55.183979] R13: ffff8801b6f2b188 R14: 0000000000000000 R15: 0000000000000000 [ 55.183983] FS: 0000000001947880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 55.183986] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 55.183996] CR2: 0000000000000080 CR3: 00000001b7cda000 CR4: 00000000001606f0 [ 55.184001] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 55.184003] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 55.184004] Stack: [ 55.184012] ffff8801d94a0880 ffff8801b6f2b180 ffff8801d94a0c50 ffff8801d94a0b58 [ 55.184017] ffff8801d948fce0 ffffffff836cc022 ffff8801d94a0cc0 ffff8801d94a0880 [ 55.184022] ffffffff836cbf50 ffff8801d948fd18 ffffffff830281f5 ffff8801d94a0cc0 [ 55.184023] Call Trace: [ 55.184031] [] pppol2tp_session_destruct+0xd2/0x110 [ 55.184035] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 55.184041] [] __sk_destruct+0x55/0x590 [ 55.184055] [] sk_destruct+0x63/0x80 [ 55.184059] [] __sk_free+0x4f/0x220 [ 55.184063] [] sk_free+0x2b/0x40 [ 55.184067] [] pppol2tp_release+0x239/0x2e0 [ 55.184074] [] __sock_release+0xd7/0x260 [ 55.184078] [] ? __sock_release+0x260/0x260 [ 55.184082] [] sock_close+0x19/0x20 [ 55.184090] [] __fput+0x263/0x700 [ 55.184094] [] ____fput+0x15/0x20 [ 55.184101] [] task_work_run+0x10c/0x180 [ 55.184107] [] exit_to_usermode_loop+0xfc/0x120 [ 55.184111] [] do_syscall_64+0x364/0x490 [ 55.184118] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 55.184181] 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 [ 55.184186] RIP [] l2tp_session_free+0x11c/0x200 [ 55.184187] RSP [ 55.184189] CR2: 0000000000000080 [ 55.184953] ---[ end trace 23ee9bb7740e99e9 ]--- [ 55.184956] Kernel panic - not syncing: Fatal exception [ 55.192987] Dumping ftrace buffer: [ 55.192989] (ftrace buffer empty) [ 55.192991] Kernel Offset: disabled [ 55.442727] Rebooting in 86400 seconds..