[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.404936] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 25.855773] random: sshd: uninitialized urandom read (32 bytes read) [ 26.326956] random: sshd: uninitialized urandom read (32 bytes read) [ 26.772414] random: sshd: uninitialized urandom read (32 bytes read) [ 26.903986] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.47' (ECDSA) to the list of known hosts. [ 32.512777] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 32.708750] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 32.717046] IP: [] l2tp_session_free+0x11c/0x200 [ 32.723468] PGD 1ca60a067 [ 32.726108] PUD 1ca646067 PMD 0 [ 32.729592] [ 32.731215] Oops: 0002 [#1] PREEMPT SMP KASAN [ 32.735682] Dumping ftrace buffer: [ 32.739196] (ftrace buffer empty) [ 32.742882] Modules linked in: [ 32.746174] CPU: 0 PID: 3799 Comm: syz-executor240 Not tainted 4.9.119-g9dc978d #23 [ 32.753937] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 32.763266] task: ffff8801bab1b000 task.stack: ffff8801d9458000 [ 32.769297] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 32.778192] RSP: 0018:ffff8801d945fca0 EFLAGS: 00010246 [ 32.783630] RAX: dffffc0000000000 RBX: ffff8801cb318a00 RCX: 0000000000000000 [ 32.790872] RDX: 1ffff10037016300 RSI: ffffffff836bf9a1 RDI: ffff8801b80b1800 [ 32.798196] RBP: ffff8801d945fcc0 R08: ffff8801bab1b8e8 R09: 0000000000000000 [ 32.805450] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b80b1680 [ 32.812697] R13: ffff8801cb318a08 R14: 0000000000000000 R15: ffffffff83015be0 [ 32.819945] FS: 00000000013a2880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 32.828147] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 32.834007] CR2: 0000000000000080 CR3: 00000001c8163000 CR4: 00000000001606f0 [ 32.841265] Stack: [ 32.843417] ffff8801b6d4c400 ffff8801cb318a00 ffff8801b6d4c7d0 ffff8801b6d4c6d8 [ 32.851405] ffff8801d945fce8 ffffffff836c72b2 ffff8801b6d4c840 ffff8801b6d4c400 [ 32.859426] ffffffff836c71e0 ffff8801d945fd20 ffffffff830230f5 ffff8801b6d4c840 [ 32.867420] Call Trace: [ 32.869985] [] pppol2tp_session_destruct+0xd2/0x110 [ 32.876640] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 32.883000] [] __sk_destruct+0x55/0x590 [ 32.888630] [] ? sock_release+0x1c0/0x1c0 [ 32.894415] [] sk_destruct+0x63/0x80 [ 32.899759] [] __sk_free+0x4f/0x220 [ 32.905011] [] sk_free+0x2b/0x40 [ 32.910003] [] pppol2tp_release+0x239/0x2e0 [ 32.915948] [] sock_release+0x96/0x1c0 [ 32.921465] [] sock_close+0x16/0x20 [ 32.926724] [] __fput+0x263/0x700 [ 32.931803] [] ____fput+0x15/0x20 [ 32.936886] [] task_work_run+0x10c/0x180 [ 32.942578] [] exit_to_usermode_loop+0xfc/0x120 [ 32.948882] [] do_syscall_64+0x364/0x490 [ 32.954570] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 32.962045] 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 f5 f0 c9 fd 4c 89 ea 48 b8 00 [ 32.989342] RIP [] l2tp_session_free+0x11c/0x200 [ 32.995889] RSP [ 32.999494] CR2: 0000000000000080 [ 33.003163] ---[ end trace 26cb9f61e73cbeaa ]--- [ 33.007901] Kernel panic - not syncing: Fatal exception [ 33.013507] Dumping ftrace buffer: [ 33.017025] (ftrace buffer empty) [ 33.020709] Kernel Offset: disabled [ 33.024310] Rebooting in 86400 seconds..