[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.149804] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 15.307548] random: sshd: uninitialized urandom read (32 bytes read) [ 15.443726] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 32.838934] urandom_read: 1 callbacks suppressed [ 32.838937] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.6' (ECDSA) to the list of known hosts. [ 38.272604] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 38.481617] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 38.489851] IP: [] l2tp_session_free+0x11c/0x200 [ 38.496278] PGD 1c048e067 [ 38.498920] PUD 1c073c067 PMD 0 [ 38.502394] [ 38.504027] Oops: 0002 [#1] PREEMPT SMP KASAN [ 38.508495] Dumping ftrace buffer: [ 38.512015] (ftrace buffer empty) [ 38.515700] Modules linked in: [ 38.518984] CPU: 1 PID: 3806 Comm: syz-executor462 Not tainted 4.9.117-g8b21e85 #71 [ 38.526754] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 38.536086] task: ffff8801b7ee4800 task.stack: ffff8801d91e0000 [ 38.542117] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 38.551775] RSP: 0018:ffff8801d91e7ca0 EFLAGS: 00010246 [ 38.557202] RAX: dffffc0000000000 RBX: ffff8801b6c10f00 RCX: 0000000000000000 [ 38.564451] RDX: 1ffff10036d823a0 RSI: ffffffff836bf8f1 RDI: ffff8801b6c11d00 [ 38.571695] RBP: ffff8801d91e7cc0 R08: ffff8801b7ee50e8 R09: 0000000000000000 [ 38.578940] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6c11b80 [ 38.586195] R13: ffff8801b6c10f08 R14: 0000000000000000 R15: ffffffff83015be0 [ 38.593445] FS: 0000000001bce880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 38.601657] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 38.607510] CR2: 0000000000000080 CR3: 00000001c83a7000 CR4: 00000000001606f0 [ 38.614768] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 38.622023] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 38.629268] Stack: [ 38.631395] ffff8801b6b9d500 ffff8801b6c10f00 ffff8801b6b9d8d0 ffff8801b6b9d7d8 [ 38.639415] ffff8801d91e7ce8 ffffffff836c7202 ffff8801b6b9d940 ffff8801b6b9d500 [ 38.647471] ffffffff836c7130 ffff8801d91e7d20 ffffffff83023095 ffff8801b6b9d940 [ 38.655456] Call Trace: [ 38.658030] [] pppol2tp_session_destruct+0xd2/0x110 [ 38.664680] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 38.670988] [] __sk_destruct+0x55/0x590 [ 38.676685] [] ? sock_release+0x1c0/0x1c0 [ 38.682484] [] sk_destruct+0x63/0x80 [ 38.687844] [] __sk_free+0x4f/0x220 [ 38.693094] [] sk_free+0x2b/0x40 [ 38.698083] [] pppol2tp_release+0x239/0x2e0 [ 38.704029] [] sock_release+0x96/0x1c0 [ 38.709546] [] sock_close+0x16/0x20 [ 38.714802] [] __fput+0x263/0x700 [ 38.719889] [] ____fput+0x15/0x20 [ 38.724970] [] task_work_run+0x10c/0x180 [ 38.730666] [] exit_to_usermode_loop+0xfc/0x120 [ 38.736959] [] do_syscall_64+0x364/0x490 [ 38.742659] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 38.749559] 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 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 38.776416] RIP [] l2tp_session_free+0x11c/0x200 [ 38.782933] RSP [ 38.786532] CR2: 0000000000000080 [ 38.790150] ---[ end trace 4b72a92a68a00dc5 ]--- [ 38.794922] Kernel panic - not syncing: Fatal exception [ 38.800617] Dumping ftrace buffer: [ 38.804129] (ftrace buffer empty) [ 38.807815] Kernel Offset: disabled [ 38.811423] Rebooting in 86400 seconds..