[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.548981] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 25.104609] random: sshd: uninitialized urandom read (32 bytes read) [ 25.524780] random: sshd: uninitialized urandom read (32 bytes read) [ 26.178539] random: sshd: uninitialized urandom read (32 bytes read) [ 34.784662] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.24' (ECDSA) to the list of known hosts. [ 40.219826] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 40.398990] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 40.407282] IP: [] l2tp_session_free+0x11c/0x200 [ 40.413718] PGD 1c4fc0067 [ 40.416364] PUD 1cb01f067 PMD 0 [ 40.419906] [ 40.421531] Oops: 0002 [#1] PREEMPT SMP KASAN [ 40.426122] Dumping ftrace buffer: [ 40.429636] (ftrace buffer empty) [ 40.433323] Modules linked in: [ 40.436616] CPU: 1 PID: 3815 Comm: syz-executor998 Not tainted 4.9.113-g47bbcd6 #10 [ 40.444394] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 40.453754] task: ffff8801b6f40000 task.stack: ffff8801d9010000 [ 40.459787] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 40.468891] RSP: 0018:ffff8801d9017ca0 EFLAGS: 00010246 [ 40.474321] RAX: dffffc0000000000 RBX: ffff8801ca71b900 RCX: 0000000000000000 [ 40.481588] RDX: 1ffff10036b4efa0 RSI: ffffffff836bcce1 RDI: ffff8801b5a77d00 [ 40.489029] RBP: ffff8801d9017cc0 R08: ffff8801b6f408e8 R09: 0000000000000000 [ 40.496281] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5a77b80 [ 40.503530] R13: ffff8801ca71b908 R14: 0000000000000000 R15: ffffffff83013be0 [ 40.510781] FS: 0000000000e67880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 40.519010] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 40.524871] CR2: 0000000000000080 CR3: 00000001c4f36000 CR4: 00000000001606f0 [ 40.532123] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 40.539382] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 40.546634] Stack: [ 40.548773] ffff8801d9131100 ffff8801ca71b900 ffff8801d91314d0 ffff8801d91313d8 [ 40.556766] ffff8801d9017ce8 ffffffff836c45f2 ffff8801d9131540 ffff8801d9131100 [ 40.564870] ffffffff836c4520 ffff8801d9017d20 ffffffff83021095 ffff8801d9131540 [ 40.572905] Call Trace: [ 40.575497] [] pppol2tp_session_destruct+0xd2/0x110 [ 40.582170] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 40.588573] [] __sk_destruct+0x55/0x590 [ 40.594208] [] ? sock_release+0x1c0/0x1c0 [ 40.600006] [] sk_destruct+0x63/0x80 [ 40.605377] [] __sk_free+0x4f/0x220 [ 40.610651] [] sk_free+0x2b/0x40 [ 40.615661] [] pppol2tp_release+0x239/0x2e0 [ 40.621640] [] sock_release+0x96/0x1c0 [ 40.627163] [] sock_close+0x16/0x20 [ 40.632433] [] __fput+0x263/0x700 [ 40.637519] [] ____fput+0x15/0x20 [ 40.642608] [] task_work_run+0x10c/0x180 [ 40.648308] [] exit_to_usermode_loop+0xfc/0x120 [ 40.654603] [] do_syscall_64+0x364/0x490 [ 40.660295] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 40.667208] 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 55 1d ca fd 4c 89 ea 48 b8 00 [ 40.694287] RIP [] l2tp_session_free+0x11c/0x200 [ 40.700807] RSP [ 40.704411] CR2: 0000000000000080 [ 40.708098] ---[ end trace eb46dfee29890023 ]--- [ 40.712864] Kernel panic - not syncing: Fatal exception [ 40.718630] Dumping ftrace buffer: [ 40.722158] (ftrace buffer empty) [ 40.725854] Kernel Offset: disabled [ 40.729461] Rebooting in 86400 seconds..