[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.416596] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.576657] random: sshd: uninitialized urandom read (32 bytes read) [ 24.023802] random: sshd: uninitialized urandom read (32 bytes read) [ 24.537666] random: sshd: uninitialized urandom read (32 bytes read) [ 24.692363] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.58' (ECDSA) to the list of known hosts. [ 30.215998] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 30.423965] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 30.432232] IP: [] l2tp_session_free+0x11c/0x200 [ 30.438655] PGD 1bd406067 [ 30.441299] PUD 1bec17067 PMD 0 [ 30.444777] [ 30.446416] Oops: 0002 [#1] PREEMPT SMP KASAN [ 30.450886] Dumping ftrace buffer: [ 30.454402] (ftrace buffer empty) [ 30.458107] Modules linked in: [ 30.461398] CPU: 0 PID: 3812 Comm: syz-executor157 Not tainted 4.9.122-g54068d6 #78 [ 30.469163] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.478521] task: ffff8801b6870000 task.stack: ffff8801b5198000 [ 30.484558] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 30.493411] RSP: 0018:ffff8801b519fca0 EFLAGS: 00010246 [ 30.498833] RAX: dffffc0000000000 RBX: ffff8801b5008500 RCX: 0000000000000000 [ 30.506080] RDX: 1ffff10036d75080 RSI: ffffffff836c39a1 RDI: ffff8801b6ba8400 [ 30.513338] RBP: ffff8801b519fcc0 R08: ffff8801b68708e8 R09: 0000000000000000 [ 30.520599] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6ba8280 [ 30.527848] R13: ffff8801b5008508 R14: 0000000000000000 R15: ffffffff83019be0 [ 30.535099] FS: 0000000001739880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 30.543299] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.549157] CR2: 0000000000000080 CR3: 00000001c3f48000 CR4: 00000000001606f0 [ 30.556406] Stack: [ 30.558534] ffff8801b550dd80 ffff8801b5008500 ffff8801b550e150 ffff8801b550e058 [ 30.566579] ffff8801b519fce8 ffffffff836cb2b2 ffff8801b550e1c0 ffff8801b550dd80 [ 30.574584] ffffffff836cb1e0 ffff8801b519fd20 ffffffff830270f5 ffff8801b550e1c0 [ 30.582590] Call Trace: [ 30.585157] [] pppol2tp_session_destruct+0xd2/0x110 [ 30.591798] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 30.598095] [] __sk_destruct+0x55/0x590 [ 30.603695] [] ? sock_release+0x1c0/0x1c0 [ 30.609476] [] sk_destruct+0x63/0x80 [ 30.614841] [] __sk_free+0x4f/0x220 [ 30.620096] [] sk_free+0x2b/0x40 [ 30.625090] [] pppol2tp_release+0x239/0x2e0 [ 30.631041] [] sock_release+0x96/0x1c0 [ 30.636556] [] sock_close+0x16/0x20 [ 30.641814] [] __fput+0x263/0x700 [ 30.646894] [] ____fput+0x15/0x20 [ 30.651984] [] task_work_run+0x10c/0x180 [ 30.657682] [] exit_to_usermode_loop+0xfc/0x120 [ 30.664014] [] do_syscall_64+0x364/0x490 [ 30.669708] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.676607] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 30.703600] RIP [] l2tp_session_free+0x11c/0x200 [ 30.710120] RSP [ 30.713720] CR2: 0000000000000080 [ 30.717707] ---[ end trace 1d2b48527370891b ]--- [ 30.722472] Kernel panic - not syncing: Fatal exception [ 30.728168] Dumping ftrace buffer: [ 30.731696] (ftrace buffer empty) [ 30.735401] Kernel Offset: disabled [ 30.739007] Rebooting in 86400 seconds..