[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.117178] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.295054] random: sshd: uninitialized urandom read (32 bytes read) [ 16.641932] random: sshd: uninitialized urandom read (32 bytes read) [ 17.112366] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.21' (ECDSA) to the list of known hosts. [ 22.784503] urandom_read: 1 callbacks suppressed [ 22.784506] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 22.986710] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 22.994969] IP: [] l2tp_session_free+0x11c/0x200 [ 23.001402] PGD 1c14ec067 [ 23.004051] PUD 1c603c067 PMD 0 [ 23.007584] [ 23.009217] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.013733] Dumping ftrace buffer: [ 23.017292] (ftrace buffer empty) [ 23.021070] Modules linked in: [ 23.024364] CPU: 1 PID: 3790 Comm: syz-executor668 Not tainted 4.9.122-g54068d6 #26 [ 23.032138] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.041472] task: ffff8801b8f6b000 task.stack: ffff8801b6030000 [ 23.047560] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.056417] RSP: 0018:ffff8801b6037ca0 EFLAGS: 00010246 [ 23.061845] RAX: dffffc0000000000 RBX: ffff8801b6774280 RCX: 0000000000000000 [ 23.069156] RDX: 1ffff10036cee4d0 RSI: ffffffff836c39a1 RDI: ffff8801b6772680 [ 23.076409] RBP: ffff8801b6037cc0 R08: ffff8801b8f6b8e8 R09: 0000000000000000 [ 23.083658] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6772500 [ 23.090904] R13: ffff8801b6774288 R14: 0000000000000000 R15: ffffffff83019be0 [ 23.098159] FS: 0000000000fbb880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 23.106374] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.112236] CR2: 0000000000000080 CR3: 00000001b87fe000 CR4: 00000000001606f0 [ 23.119490] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.126742] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.133996] Stack: [ 23.136124] ffff8801b7e1cc80 ffff8801b6774280 ffff8801b7e1d050 ffff8801b7e1cf58 [ 23.144154] ffff8801b6037ce8 ffffffff836cb2b2 ffff8801b7e1d0c0 ffff8801b7e1cc80 [ 23.152236] ffffffff836cb1e0 ffff8801b6037d20 ffffffff830270f5 ffff8801b7e1d0c0 [ 23.160507] Call Trace: [ 23.163074] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.169718] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.176025] [] __sk_destruct+0x55/0x590 [ 23.181632] [] ? sock_release+0x1c0/0x1c0 [ 23.187410] [] sk_destruct+0x63/0x80 [ 23.192751] [] __sk_free+0x4f/0x220 [ 23.198004] [] sk_free+0x2b/0x40 [ 23.203047] [] pppol2tp_release+0x239/0x2e0 [ 23.209003] [] sock_release+0x96/0x1c0 [ 23.214524] [] sock_close+0x16/0x20 [ 23.219791] [] __fput+0x263/0x700 [ 23.224874] [] ____fput+0x15/0x20 [ 23.229963] [] task_work_run+0x10c/0x180 [ 23.235700] [] exit_to_usermode_loop+0xfc/0x120 [ 23.242010] [] do_syscall_64+0x364/0x490 [ 23.247714] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.254616] 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 [ 23.281678] RIP [] l2tp_session_free+0x11c/0x200 [ 23.288227] RSP [ 23.288230] CR2: 0000000000000080 [ 23.291502] ---[ end trace 00ddf24243a0dcc8 ]--- [ 23.291507] Kernel panic - not syncing: Fatal exception [ 23.292325] Dumping ftrace buffer: [ 23.292328] (ftrace buffer empty) [ 23.292331] Kernel Offset: disabled [ 23.316677] Rebooting in 86400 seconds..