[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.898091] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 25.934265] random: sshd: uninitialized urandom read (32 bytes read) [ 26.405820] random: sshd: uninitialized urandom read (32 bytes read) [ 26.940834] random: sshd: uninitialized urandom read (32 bytes read) [ 27.082225] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.34' (ECDSA) to the list of known hosts. [ 32.497796] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 32.707688] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 32.716386] IP: [] l2tp_session_free+0x11c/0x200 [ 32.722830] PGD 1cc51c067 [ 32.725490] PUD 1ccbd7067 PMD 0 [ 32.729113] [ 32.730747] Oops: 0002 [#1] PREEMPT SMP KASAN [ 32.735223] Dumping ftrace buffer: [ 32.738747] (ftrace buffer empty) [ 32.742444] Modules linked in: [ 32.745851] CPU: 1 PID: 3806 Comm: syz-executor076 Not tainted 4.9.120-gf85543b #24 [ 32.753631] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 32.763106] task: ffff8801b6d44800 task.stack: ffff8801b5a40000 [ 32.769300] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 32.778173] RSP: 0018:ffff8801b5a47ca0 EFLAGS: 00010246 [ 32.783608] RAX: dffffc0000000000 RBX: ffff8801c9537b80 RCX: 0000000000000000 [ 32.790969] RDX: 1ffff10036b1db00 RSI: ffffffff836c29a1 RDI: ffff8801b58ed800 [ 32.798362] RBP: ffff8801b5a47cc0 R08: ffff8801b6d450e8 R09: 0000000000000000 [ 32.805628] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b58ed680 [ 32.813049] R13: ffff8801c9537b88 R14: 0000000000000000 R15: ffffffff83018be0 [ 32.820317] FS: 0000000001c99880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 32.828525] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 32.834395] CR2: 0000000000000080 CR3: 00000001c965e000 CR4: 00000000001606f0 [ 32.841915] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 32.849350] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 32.856604] Stack: [ 32.858739] ffff8801b594aa80 ffff8801c9537b80 ffff8801b594ae50 ffff8801b594ad58 [ 32.866811] ffff8801b5a47ce8 ffffffff836ca2b2 ffff8801b594aec0 ffff8801b594aa80 [ 32.874936] ffffffff836ca1e0 ffff8801b5a47d20 ffffffff830260f5 ffff8801b594aec0 [ 32.882974] Call Trace: [ 32.885557] [] pppol2tp_session_destruct+0xd2/0x110 [ 32.892210] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 32.898517] [] __sk_destruct+0x55/0x590 [ 32.904127] [] ? sock_release+0x1c0/0x1c0 [ 32.910044] [] sk_destruct+0x63/0x80 [ 32.915396] [] __sk_free+0x4f/0x220 [ 32.920658] [] sk_free+0x2b/0x40 [ 32.925732] [] pppol2tp_release+0x239/0x2e0 [ 32.931693] [] sock_release+0x96/0x1c0 [ 32.937214] [] sock_close+0x16/0x20 [ 32.942479] [] __fput+0x263/0x700 [ 32.947577] [] ____fput+0x15/0x20 [ 32.952792] [] task_work_run+0x10c/0x180 [ 32.958583] [] exit_to_usermode_loop+0xfc/0x120 [ 32.964892] [] do_syscall_64+0x364/0x490 [ 32.970705] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 32.977618] 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 15 de c9 fd 4c 89 ea 48 b8 00 [ 33.005608] RIP [] l2tp_session_free+0x11c/0x200 [ 33.012139] RSP [ 33.015746] CR2: 0000000000000080 [ 33.019796] ---[ end trace 8e1ac7e3169a7e44 ]--- [ 33.024558] Kernel panic - not syncing: Fatal exception [ 33.030330] Dumping ftrace buffer: [ 33.033860] (ftrace buffer empty) [ 33.037555] Kernel Offset: disabled [ 33.041163] Rebooting in 86400 seconds..