[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.813016] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.895425] random: sshd: uninitialized urandom read (32 bytes read) [ 16.172386] random: sshd: uninitialized urandom read (32 bytes read) [ 16.685258] random: sshd: uninitialized urandom read (32 bytes read) [ 23.447054] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.59' (ECDSA) to the list of known hosts. [ 29.013404] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 29.234690] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 29.242912] IP: [] l2tp_session_free+0x11c/0x200 [ 29.249328] PGD 1cb0c4067 [ 29.251969] PUD 1cb62e067 PMD 0 [ 29.255514] [ 29.257136] Oops: 0002 [#1] PREEMPT SMP KASAN [ 29.261639] Dumping ftrace buffer: [ 29.265155] (ftrace buffer empty) [ 29.268877] Modules linked in: [ 29.272173] CPU: 0 PID: 3808 Comm: syz-executor874 Not tainted 4.9.122-g54068d6 #78 [ 29.279938] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 29.289386] task: ffff8801b89f9800 task.stack: ffff8801b50b8000 [ 29.295412] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 29.304263] RSP: 0018:ffff8801b50bfca0 EFLAGS: 00010246 [ 29.309688] RAX: dffffc0000000000 RBX: ffff8801c840f400 RCX: 0000000000000000 [ 29.316935] RDX: 1ffff10036b65d20 RSI: ffffffff836c39a1 RDI: ffff8801b5b2e900 [ 29.324460] RBP: ffff8801b50bfcc0 R08: ffff8801b89fa0e8 R09: 0000000000000000 [ 29.331708] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5b2e780 [ 29.338952] R13: ffff8801c840f408 R14: 0000000000000000 R15: ffffffff83019be0 [ 29.346204] FS: 0000000000847880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 29.354407] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 29.360262] CR2: 0000000000000080 CR3: 00000001bf9a4000 CR4: 00000000001606f0 [ 29.367506] Stack: [ 29.369633] ffff8801d9453b80 ffff8801c840f400 ffff8801d9453f50 ffff8801d9453e58 [ 29.377624] ffff8801b50bfce8 ffffffff836cb2b2 ffff8801d9453fc0 ffff8801d9453b80 [ 29.385610] ffffffff836cb1e0 ffff8801b50bfd20 ffffffff830270f5 ffff8801d9453fc0 [ 29.393593] Call Trace: [ 29.396156] [] pppol2tp_session_destruct+0xd2/0x110 [ 29.402883] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 29.409179] [] __sk_destruct+0x55/0x590 [ 29.414778] [] ? sock_release+0x1c0/0x1c0 [ 29.420550] [] sk_destruct+0x63/0x80 [ 29.425892] [] __sk_free+0x4f/0x220 [ 29.431309] [] sk_free+0x2b/0x40 [ 29.436314] [] pppol2tp_release+0x239/0x2e0 [ 29.442269] [] sock_release+0x96/0x1c0 [ 29.447785] [] sock_close+0x16/0x20 [ 29.453043] [] __fput+0x263/0x700 [ 29.458128] [] ____fput+0x15/0x20 [ 29.463216] [] task_work_run+0x10c/0x180 [ 29.468917] [] exit_to_usermode_loop+0xfc/0x120 [ 29.475245] [] do_syscall_64+0x364/0x490 [ 29.480940] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 29.487858] 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 [ 29.514867] RIP [] l2tp_session_free+0x11c/0x200 [ 29.521377] RSP [ 29.524978] CR2: 0000000000000080 [ 29.530143] ---[ end trace f008a50e5fee7f9a ]--- [ 29.534921] Kernel panic - not syncing: Fatal exception [ 29.540599] Dumping ftrace buffer: [ 29.544211] (ftrace buffer empty) [ 29.547897] Kernel Offset: disabled [ 29.551557] Rebooting in 86400 seconds..