[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.997368] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.068824] random: sshd: uninitialized urandom read (32 bytes read) [ 27.614842] random: sshd: uninitialized urandom read (32 bytes read) [ 28.091066] random: sshd: uninitialized urandom read (32 bytes read) [ 28.229171] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.41' (ECDSA) to the list of known hosts. [ 33.852051] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.072221] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.080584] IP: [] l2tp_session_free+0x11c/0x200 [ 34.087020] PGD 1c6163067 [ 34.089662] PUD 1c6254067 PMD 0 [ 34.093146] [ 34.094766] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.099236] Dumping ftrace buffer: [ 34.102807] (ftrace buffer empty) [ 34.106497] Modules linked in: [ 34.109780] CPU: 1 PID: 3720 Comm: syz-executor421 Not tainted 4.9.124-g6a1b592 #30 [ 34.117552] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.126886] task: ffff8801c06ee000 task.stack: ffff8801bf988000 [ 34.132916] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.141769] RSP: 0018:ffff8801bf98fc98 EFLAGS: 00010246 [ 34.147310] RAX: dffffc0000000000 RBX: ffff8801c024b680 RCX: 0000000000000000 [ 34.154555] RDX: 1ffff100381314d0 RSI: ffffffff836c4711 RDI: ffff8801c098a680 [ 34.161794] RBP: ffff8801bf98fcb8 R08: ffff8801c06ee8e8 R09: 0000000000000000 [ 34.169035] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c098a500 [ 34.176336] R13: ffff8801c024b688 R14: 0000000000000000 R15: 0000000000000000 [ 34.183585] FS: 0000000001a10880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 34.191788] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.197643] CR2: 0000000000000080 CR3: 00000001c616f000 CR4: 00000000001606f0 [ 34.204895] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 34.212134] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 34.219372] Stack: [ 34.221495] ffff8801bf9b0000 ffff8801c024b680 ffff8801bf9b03d0 ffff8801bf9b02d8 [ 34.229471] ffff8801bf98fce0 ffffffff836cc022 ffff8801bf9b0440 ffff8801bf9b0000 [ 34.237446] ffffffff836cbf50 ffff8801bf98fd18 ffffffff830281f5 ffff8801bf9b0440 [ 34.245440] Call Trace: [ 34.248003] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.254662] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.260959] [] __sk_destruct+0x55/0x590 [ 34.266557] [] sk_destruct+0x63/0x80 [ 34.272313] [] __sk_free+0x4f/0x220 [ 34.277643] [] sk_free+0x2b/0x40 [ 34.282639] [] pppol2tp_release+0x239/0x2e0 [ 34.288583] [] __sock_release+0xd7/0x260 [ 34.294264] [] ? __sock_release+0x260/0x260 [ 34.300207] [] sock_close+0x19/0x20 [ 34.305457] [] __fput+0x263/0x700 [ 34.310533] [] ____fput+0x15/0x20 [ 34.315617] [] task_work_run+0x10c/0x180 [ 34.321300] [] exit_to_usermode_loop+0xfc/0x120 [ 34.327586] [] do_syscall_64+0x364/0x490 [ 34.333275] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.340168] 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 a5 c5 c9 fd 4c 89 ea 48 b8 00 [ 34.366924] RIP [] l2tp_session_free+0x11c/0x200 [ 34.373426] RSP [ 34.377058] CR2: 0000000000000080 [ 34.380704] ---[ end trace 457b5fbc888bdc3c ]--- [ 34.385478] Kernel panic - not syncing: Fatal exception [ 34.391156] Dumping ftrace buffer: [ 34.394671] (ftrace buffer empty) [ 34.398354] Kernel Offset: disabled [ 34.401958] Rebooting in 86400 seconds..