[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.473518] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.235729] random: sshd: uninitialized urandom read (32 bytes read) [ 20.692290] random: sshd: uninitialized urandom read (32 bytes read) [ 21.184931] random: sshd: uninitialized urandom read (32 bytes read) [ 21.331677] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.17' (ECDSA) to the list of known hosts. [ 26.973238] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.151487] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.159752] IP: [] l2tp_session_free+0x11c/0x200 [ 27.166213] PGD 1c9554067 [ 27.169346] PUD 1c95e6067 PMD 0 [ 27.173155] [ 27.174794] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.179306] Dumping ftrace buffer: [ 27.182866] (ftrace buffer empty) [ 27.186693] Modules linked in: [ 27.190013] CPU: 0 PID: 3804 Comm: syz-executor175 Not tainted 4.9.123-g8dd3fc2 #27 [ 27.197855] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.207355] task: ffff8801b8ee1800 task.stack: ffff8801cb620000 [ 27.213513] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.222503] RSP: 0018:ffff8801cb627ca0 EFLAGS: 00010246 [ 27.228140] RAX: dffffc0000000000 RBX: ffff8801b83dca00 RCX: 0000000000000000 [ 27.235493] RDX: 1ffff10036d90830 RSI: ffffffff836c4991 RDI: ffff8801b6c84180 [ 27.242756] RBP: ffff8801cb627cc0 R08: ffff8801b8ee20e8 R09: 0000000000000000 [ 27.250072] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6c84000 [ 27.257439] R13: ffff8801b83dca08 R14: 0000000000000000 R15: ffffffff8301abe0 [ 27.265081] FS: 000000000121c880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 27.273298] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.279256] CR2: 0000000000000080 CR3: 00000001b934b000 CR4: 00000000001606f0 [ 27.286603] Stack: [ 27.288985] ffff8801b74ff700 ffff8801b83dca00 ffff8801b74ffad0 ffff8801b74ff9d8 [ 27.297075] ffff8801cb627ce8 ffffffff836cc2a2 ffff8801b74ffb40 ffff8801b74ff700 [ 27.305180] ffffffff836cc1d0 ffff8801cb627d20 ffffffff830280f5 ffff8801b74ffb40 [ 27.313251] Call Trace: [ 27.316248] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.323347] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.329673] [] __sk_destruct+0x55/0x590 [ 27.335402] [] ? sock_release+0x1c0/0x1c0 [ 27.341190] [] sk_destruct+0x63/0x80 [ 27.346539] [] __sk_free+0x4f/0x220 [ 27.351830] [] sk_free+0x2b/0x40 [ 27.356869] [] pppol2tp_release+0x239/0x2e0 [ 27.363072] [] sock_release+0x96/0x1c0 [ 27.368600] [] sock_close+0x16/0x20 [ 27.374129] [] __fput+0x263/0x700 [ 27.379347] [] ____fput+0x15/0x20 [ 27.384878] [] task_work_run+0x10c/0x180 [ 27.390593] [] exit_to_usermode_loop+0xfc/0x120 [ 27.396999] [] do_syscall_64+0x364/0x490 [ 27.402966] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.410035] 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 e5 c3 c9 fd 4c 89 ea 48 b8 00 [ 27.438847] RIP [] l2tp_session_free+0x11c/0x200 [ 27.445384] RSP [ 27.449220] CR2: 0000000000000080 [ 27.453374] ---[ end trace 903da3fcbaca4e03 ]--- [ 27.458127] Kernel panic - not syncing: Fatal exception [ 27.464042] Dumping ftrace buffer: [ 27.467579] (ftrace buffer empty) [ 27.471404] Kernel Offset: disabled [ 27.475269] Rebooting in 86400 seconds..