[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.244778] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.939191] random: sshd: uninitialized urandom read (32 bytes read) [ 18.301760] random: sshd: uninitialized urandom read (32 bytes read) [ 19.267836] random: sshd: uninitialized urandom read (32 bytes read) [ 19.395864] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.22' (ECDSA) to the list of known hosts. [ 24.822072] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.014054] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.022341] IP: [] l2tp_session_free+0x11c/0x200 [ 25.028775] PGD 1bfbd6067 [ 25.031425] PUD 1be4b5067 PMD 0 [ 25.034975] [ 25.036601] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.041079] Dumping ftrace buffer: [ 25.044606] (ftrace buffer empty) [ 25.048300] Modules linked in: [ 25.051599] CPU: 1 PID: 3809 Comm: syz-executor492 Not tainted 4.9.113-g90e7a90 #16 [ 25.059378] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.068752] task: ffff8801b733b000 task.stack: ffff8801d9840000 [ 25.074795] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.083687] RSP: 0018:ffff8801d9847ca0 EFLAGS: 00010246 [ 25.089124] RAX: dffffc0000000000 RBX: ffff8801b5461900 RCX: 0000000000000000 [ 25.096385] RDX: 1ffff10036a8c080 RSI: ffffffff836bdee1 RDI: ffff8801b5460400 [ 25.103633] RBP: ffff8801d9847cc0 R08: ffff8801b733b8e8 R09: 0000000000000000 [ 25.110895] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5460280 [ 25.118149] R13: ffff8801b5461908 R14: 0000000000000000 R15: ffffffff83014be0 [ 25.125409] FS: 0000000000b9f880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 25.133618] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.139495] CR2: 0000000000000080 CR3: 00000001c0be5000 CR4: 00000000001606f0 [ 25.146758] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.154024] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.161287] Stack: [ 25.163414] ffff8801b57b6e80 ffff8801b5461900 ffff8801b57b7250 ffff8801b57b7158 [ 25.171438] ffff8801d9847ce8 ffffffff836c57f2 ffff8801b57b72c0 ffff8801b57b6e80 [ 25.179470] ffffffff836c5720 ffff8801d9847d20 ffffffff83022095 ffff8801b57b72c0 [ 25.187483] Call Trace: [ 25.190054] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.196713] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.203037] [] __sk_destruct+0x55/0x590 [ 25.208654] [] ? sock_release+0x1c0/0x1c0 [ 25.214448] [] sk_destruct+0x63/0x80 [ 25.219792] [] __sk_free+0x4f/0x220 [ 25.225061] [] sk_free+0x2b/0x40 [ 25.230073] [] pppol2tp_release+0x239/0x2e0 [ 25.236035] [] sock_release+0x96/0x1c0 [ 25.241553] [] sock_close+0x16/0x20 [ 25.246833] [] __fput+0x263/0x700 [ 25.251948] [] ____fput+0x15/0x20 [ 25.257050] [] task_work_run+0x10c/0x180 [ 25.262751] [] exit_to_usermode_loop+0xfc/0x120 [ 25.269053] [] do_syscall_64+0x364/0x490 [ 25.274753] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.281661] 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 55 0b ca fd 4c 89 ea 48 b8 00 [ 25.309058] RIP [] l2tp_session_free+0x11c/0x200 [ 25.315592] RSP [ 25.319212] CR2: 0000000000000080 [ 25.322724] ---[ end trace b673b2b827310d49 ]--- [ 25.327495] Kernel panic - not syncing: Fatal exception [ 25.333553] Dumping ftrace buffer: [ 25.337091] (ftrace buffer empty) [ 25.340792] Kernel Offset: disabled [ 25.344398] Rebooting in 86400 seconds..