[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.957949] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.836085] random: sshd: uninitialized urandom read (32 bytes read) [ 21.241436] random: sshd: uninitialized urandom read (32 bytes read) [ 21.783093] random: sshd: uninitialized urandom read (32 bytes read) [ 26.200842] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.15' (ECDSA) to the list of known hosts. [ 31.761628] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 31.983833] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 31.992066] IP: [] l2tp_session_free+0x11c/0x200 [ 31.998486] PGD 1c6c85067 [ 32.001137] PUD 1c83e5067 PMD 0 [ 32.004643] [ 32.006268] Oops: 0002 [#1] PREEMPT SMP KASAN [ 32.010744] Dumping ftrace buffer: [ 32.014262] (ftrace buffer empty) [ 32.017955] Modules linked in: [ 32.021250] CPU: 0 PID: 3803 Comm: syz-executor219 Not tainted 4.9.121-g681e57b #77 [ 32.029064] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 32.038405] task: ffff8801b860e000 task.stack: ffff8801d95b8000 [ 32.044450] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 32.053313] RSP: 0018:ffff8801d95bfca0 EFLAGS: 00010246 [ 32.058835] RAX: dffffc0000000000 RBX: ffff8801c6df8500 RCX: 0000000000000000 [ 32.066091] RDX: 1ffff1003904e9c0 RSI: ffffffff836c29a1 RDI: ffff8801c8274e00 [ 32.073351] RBP: ffff8801d95bfcc0 R08: ffff8801b860e8e8 R09: 0000000000000000 [ 32.080602] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c8274c80 [ 32.087858] R13: ffff8801c6df8508 R14: 0000000000000000 R15: ffffffff83018be0 [ 32.095115] FS: 000000000111f880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 32.103317] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 32.109225] CR2: 0000000000000080 CR3: 00000001c3aa9000 CR4: 00000000001606f0 [ 32.116499] Stack: [ 32.118727] ffff8801b59a7700 ffff8801c6df8500 ffff8801b59a7ad0 ffff8801b59a79d8 [ 32.126774] ffff8801d95bfce8 ffffffff836ca2b2 ffff8801b59a7b40 ffff8801b59a7700 [ 32.134767] ffffffff836ca1e0 ffff8801d95bfd20 ffffffff830260f5 ffff8801b59a7b40 [ 32.142802] Call Trace: [ 32.145366] [] pppol2tp_session_destruct+0xd2/0x110 [ 32.152012] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 32.158314] [] __sk_destruct+0x55/0x590 [ 32.163938] [] ? sock_release+0x1c0/0x1c0 [ 32.169713] [] sk_destruct+0x63/0x80 [ 32.175054] [] __sk_free+0x4f/0x220 [ 32.180307] [] sk_free+0x2b/0x40 [ 32.185300] [] pppol2tp_release+0x239/0x2e0 [ 32.191361] [] sock_release+0x96/0x1c0 [ 32.196875] [] sock_close+0x16/0x20 [ 32.202144] [] __fput+0x263/0x700 [ 32.207224] [] ____fput+0x15/0x20 [ 32.212306] [] task_work_run+0x10c/0x180 [ 32.217997] [] exit_to_usermode_loop+0xfc/0x120 [ 32.224511] [] do_syscall_64+0x364/0x490 [ 32.230221] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 32.237122] 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 65 df c9 fd 4c 89 ea 48 b8 00 [ 32.264216] RIP [] l2tp_session_free+0x11c/0x200 [ 32.270723] RSP [ 32.274371] CR2: 0000000000000080 [ 32.278048] ---[ end trace 8c03bef0e4cc9033 ]--- [ 32.282784] Kernel panic - not syncing: Fatal exception [ 32.288360] Dumping ftrace buffer: [ 32.291876] (ftrace buffer empty) [ 32.295562] Kernel Offset: disabled [ 32.299162] Rebooting in 86400 seconds..