[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.709081] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.200551] random: sshd: uninitialized urandom read (32 bytes read) [ 18.611138] random: sshd: uninitialized urandom read (32 bytes read) [ 19.705726] random: sshd: uninitialized urandom read (32 bytes read) [ 19.842296] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.61' (ECDSA) to the list of known hosts. [ 25.374137] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.592284] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.600527] IP: [] l2tp_session_free+0x11c/0x200 [ 25.606953] PGD 1ba5a1067 [ 25.609590] PUD 1ba5c6067 PMD 0 [ 25.613078] [ 25.614713] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.619176] Dumping ftrace buffer: [ 25.622684] (ftrace buffer empty) [ 25.626363] Modules linked in: [ 25.629649] CPU: 0 PID: 3801 Comm: syz-executor576 Not tainted 4.9.116-g0137ea2 #70 [ 25.637411] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.646739] task: ffff8801b80a3000 task.stack: ffff8801c6118000 [ 25.652777] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.661633] RSP: 0018:ffff8801c611fca0 EFLAGS: 00010246 [ 25.667053] RAX: dffffc0000000000 RBX: ffff8801c8439400 RCX: 0000000000000000 [ 25.674296] RDX: 1ffff100390ba880 RSI: ffffffff836be8f1 RDI: ffff8801c85d4400 [ 25.681535] RBP: ffff8801c611fcc0 R08: ffff8801b80a38e8 R09: 0000000000000000 [ 25.688781] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c85d4280 [ 25.696039] R13: ffff8801c8439408 R14: 0000000000000000 R15: ffffffff83014be0 [ 25.703297] FS: 0000000001198880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 25.711492] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.717362] CR2: 0000000000000080 CR3: 00000001bdfac000 CR4: 00000000001606f0 [ 25.724611] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.731853] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.739092] Stack: [ 25.741211] ffff8801d900e600 ffff8801c8439400 ffff8801d900e9d0 ffff8801d900e8d8 [ 25.749206] ffff8801c611fce8 ffffffff836c6202 ffff8801d900ea40 ffff8801d900e600 [ 25.757178] ffffffff836c6130 ffff8801c611fd20 ffffffff83022095 ffff8801d900ea40 [ 25.765167] Call Trace: [ 25.767731] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.774384] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.780675] [] __sk_destruct+0x55/0x590 [ 25.786274] [] ? sock_release+0x1c0/0x1c0 [ 25.792045] [] sk_destruct+0x63/0x80 [ 25.797392] [] __sk_free+0x4f/0x220 [ 25.802647] [] sk_free+0x2b/0x40 [ 25.807637] [] pppol2tp_release+0x239/0x2e0 [ 25.813587] [] sock_release+0x96/0x1c0 [ 25.819108] [] sock_close+0x16/0x20 [ 25.824361] [] __fput+0x263/0x700 [ 25.829437] [] ____fput+0x15/0x20 [ 25.834516] [] task_work_run+0x10c/0x180 [ 25.840205] [] exit_to_usermode_loop+0xfc/0x120 [ 25.846495] [] do_syscall_64+0x364/0x490 [ 25.852184] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.859086] 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 01 ca fd 4c 89 ea 48 b8 00 [ 25.885833] RIP [] l2tp_session_free+0x11c/0x200 [ 25.892332] RSP [ 25.895927] CR2: 0000000000000080 [ 25.899673] ---[ end trace 19c7c93ecc10facf ]--- [ 25.904434] Kernel panic - not syncing: Fatal exception [ 25.910183] Dumping ftrace buffer: [ 25.913705] (ftrace buffer empty) [ 25.917386] Kernel Offset: disabled [ 25.920983] Rebooting in 86400 seconds..