[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.354017] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.439979] random: sshd: uninitialized urandom read (32 bytes read) [ 16.927518] random: sshd: uninitialized urandom read (32 bytes read) [ 17.379513] random: sshd: uninitialized urandom read (32 bytes read) [ 17.519162] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.15' (ECDSA) to the list of known hosts. [ 23.265791] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.462996] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.471231] IP: [] l2tp_session_free+0x11c/0x200 [ 23.477664] PGD 1bdd64067 [ 23.480307] PUD 1bdd0e067 PMD 0 [ 23.483795] [ 23.485413] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.489877] Dumping ftrace buffer: [ 23.493397] (ftrace buffer empty) [ 23.497092] Modules linked in: [ 23.500393] CPU: 1 PID: 3793 Comm: syz-executor451 Not tainted 4.9.120-gf85543b #24 [ 23.508168] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.517496] task: ffff8801b7a13000 task.stack: ffff8801b6400000 [ 23.523539] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.532487] RSP: 0018:ffff8801b6407ca0 EFLAGS: 00010246 [ 23.537912] RAX: dffffc0000000000 RBX: ffff8801ca16f900 RCX: 0000000000000000 [ 23.545173] RDX: 1ffff100394333a0 RSI: ffffffff836c29a1 RDI: ffff8801ca199d00 [ 23.552420] RBP: ffff8801b6407cc0 R08: ffff8801b7a138e8 R09: 0000000000000000 [ 23.559669] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ca199b80 [ 23.566921] R13: ffff8801ca16f908 R14: 0000000000000000 R15: ffffffff83018be0 [ 23.574168] FS: 0000000001252880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 23.582373] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.588232] CR2: 0000000000000080 CR3: 00000001bcc1d000 CR4: 00000000001606f0 [ 23.595505] Stack: [ 23.597637] ffff8801b704cc80 ffff8801ca16f900 ffff8801b704d050 ffff8801b704cf58 [ 23.605774] ffff8801b6407ce8 ffffffff836ca2b2 ffff8801b704d0c0 ffff8801b704cc80 [ 23.613769] ffffffff836ca1e0 ffff8801b6407d20 ffffffff830260f5 ffff8801b704d0c0 [ 23.621782] Call Trace: [ 23.624362] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.631018] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.637321] [] __sk_destruct+0x55/0x590 [ 23.642922] [] ? sock_release+0x1c0/0x1c0 [ 23.648702] [] sk_destruct+0x63/0x80 [ 23.654039] [] __sk_free+0x4f/0x220 [ 23.659298] [] sk_free+0x2b/0x40 [ 23.664285] [] pppol2tp_release+0x239/0x2e0 [ 23.670230] [] sock_release+0x96/0x1c0 [ 23.675926] [] sock_close+0x16/0x20 [ 23.681310] [] __fput+0x263/0x700 [ 23.686413] [] ____fput+0x15/0x20 [ 23.691513] [] task_work_run+0x10c/0x180 [ 23.697206] [] exit_to_usermode_loop+0xfc/0x120 [ 23.703497] [] do_syscall_64+0x364/0x490 [ 23.709195] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.716282] 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 15 de c9 fd 4c 89 ea 48 b8 00 [ 23.743851] RIP [] l2tp_session_free+0x11c/0x200 [ 23.750478] RSP [ 23.754080] CR2: 0000000000000080 [ 23.758560] ---[ end trace 9271b801b7ea3b7a ]--- [ 23.763338] Kernel panic - not syncing: Fatal exception [ 23.769330] Dumping ftrace buffer: [ 23.772893] (ftrace buffer empty) [ 23.776586] Kernel Offset: disabled [ 23.780287] Rebooting in 86400 seconds..