[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.899931] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.830396] random: sshd: uninitialized urandom read (32 bytes read) [ 19.237008] random: sshd: uninitialized urandom read (32 bytes read) [ 19.768598] random: sshd: uninitialized urandom read (32 bytes read) [ 19.906501] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.19' (ECDSA) to the list of known hosts. [ 25.335068] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.548456] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.556725] IP: [] l2tp_session_free+0x11c/0x200 [ 25.563169] PGD 1b6921067 [ 25.565812] PUD 1b6915067 PMD 0 [ 25.569286] [ 25.570906] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.575376] Dumping ftrace buffer: [ 25.578888] (ftrace buffer empty) [ 25.582574] Modules linked in: [ 25.585866] CPU: 0 PID: 3797 Comm: syz-executor039 Not tainted 4.9.119-g9dc978d #23 [ 25.593696] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.603054] task: ffff8801b68f4800 task.stack: ffff8801d9b88000 [ 25.609092] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.617945] RSP: 0018:ffff8801d9b8fca0 EFLAGS: 00010246 [ 25.623368] RAX: dffffc0000000000 RBX: ffff8801c8e58280 RCX: 0000000000000000 [ 25.630701] RDX: 1ffff100391bf030 RSI: ffffffff836bf9a1 RDI: ffff8801c8df8180 [ 25.637961] RBP: ffff8801d9b8fcc0 R08: ffff8801b68f50e8 R09: 0000000000000000 [ 25.645236] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c8df8000 [ 25.652483] R13: ffff8801c8e58288 R14: 0000000000000000 R15: ffffffff83015be0 [ 25.659741] FS: 0000000000fc0880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 25.667945] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.673805] CR2: 0000000000000080 CR3: 00000001c6fd1000 CR4: 00000000001606f0 [ 25.681054] Stack: [ 25.683181] ffff8801d94aaa80 ffff8801c8e58280 ffff8801d94aae50 ffff8801d94aad58 [ 25.691338] ffff8801d9b8fce8 ffffffff836c72b2 ffff8801d94aaec0 ffff8801d94aaa80 [ 25.699341] ffffffff836c71e0 ffff8801d9b8fd20 ffffffff830230f5 ffff8801d94aaec0 [ 25.707336] Call Trace: [ 25.709908] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.716566] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.722872] [] __sk_destruct+0x55/0x590 [ 25.728485] [] ? sock_release+0x1c0/0x1c0 [ 25.734268] [] sk_destruct+0x63/0x80 [ 25.739613] [] __sk_free+0x4f/0x220 [ 25.744868] [] sk_free+0x2b/0x40 [ 25.749868] [] pppol2tp_release+0x239/0x2e0 [ 25.755827] [] sock_release+0x96/0x1c0 [ 25.761348] [] sock_close+0x16/0x20 [ 25.766606] [] __fput+0x263/0x700 [ 25.771692] [] ____fput+0x15/0x20 [ 25.776785] [] task_work_run+0x10c/0x180 [ 25.782480] [] exit_to_usermode_loop+0xfc/0x120 [ 25.788784] [] do_syscall_64+0x364/0x490 [ 25.794478] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.801382] 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 [ 25.828458] RIP [] l2tp_session_free+0x11c/0x200 [ 25.834971] RSP [ 25.838571] CR2: 0000000000000080 [ 25.842331] ---[ end trace f776e0339d7bb140 ]--- [ 25.847081] Kernel panic - not syncing: Fatal exception [ 25.852734] Dumping ftrace buffer: [ 25.856254] (ftrace buffer empty) [ 25.859939] Kernel Offset: disabled [ 25.863548] Rebooting in 86400 seconds..