[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.449902] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 28.073691] random: sshd: uninitialized urandom read (32 bytes read) [ 28.276281] random: sshd: uninitialized urandom read (32 bytes read) [ 28.751388] random: sshd: uninitialized urandom read (32 bytes read) [ 40.998121] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.35' (ECDSA) to the list of known hosts. [ 46.545355] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 46.749030] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 46.757246] IP: [] l2tp_session_free+0x11c/0x200 [ 46.763687] PGD 1c0988067 [ 46.766328] PUD 1c079e067 PMD 0 [ 46.769802] [ 46.771420] Oops: 0002 [#1] PREEMPT SMP KASAN [ 46.775886] Dumping ftrace buffer: [ 46.779395] (ftrace buffer empty) [ 46.783076] Modules linked in: [ 46.786367] CPU: 0 PID: 3744 Comm: syz-executor886 Not tainted 4.9.123-g7fa8c15 #28 [ 46.794143] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 46.803488] task: ffff8801be694800 task.stack: ffff8801be2b0000 [ 46.809518] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 46.818458] RSP: 0018:ffff8801be2b7c98 EFLAGS: 00010246 [ 46.823881] RAX: dffffc0000000000 RBX: ffff8801be562000 RCX: 0000000000000000 [ 46.831126] RDX: 1ffff10037d81170 RSI: ffffffff836c4a91 RDI: ffff8801bec08b80 [ 46.838369] RBP: ffff8801be2b7cb8 R08: ffff8801be6950e8 R09: 0000000000000000 [ 46.845743] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bec08a00 [ 46.852988] R13: ffff8801be562008 R14: 0000000000000000 R15: 0000000000000000 [ 46.860240] FS: 0000000001fb7880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 46.868518] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 46.874379] CR2: 0000000000000080 CR3: 00000001cdbcf000 CR4: 00000000001606f0 [ 46.881624] Stack: [ 46.883744] ffff8801be2a0000 ffff8801be562000 ffff8801be2a03d0 ffff8801be2a02d8 [ 46.891729] ffff8801be2b7ce0 ffffffff836cc3a2 ffff8801be2a0440 ffff8801be2a0000 [ 46.899777] ffffffff836cc2d0 ffff8801be2b7d18 ffffffff830281f5 ffff8801be2a0440 [ 46.907777] Call Trace: [ 46.910342] [] pppol2tp_session_destruct+0xd2/0x110 [ 46.916981] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 46.923271] [] __sk_destruct+0x55/0x590 [ 46.928883] [] sk_destruct+0x63/0x80 [ 46.934231] [] __sk_free+0x4f/0x220 [ 46.939484] [] sk_free+0x2b/0x40 [ 46.944473] [] pppol2tp_release+0x239/0x2e0 [ 46.950416] [] __sock_release+0xd7/0x260 [ 46.956102] [] ? __sock_release+0x260/0x260 [ 46.962047] [] sock_close+0x19/0x20 [ 46.967299] [] __fput+0x263/0x700 [ 46.972376] [] ____fput+0x15/0x20 [ 46.977453] [] task_work_run+0x10c/0x180 [ 46.983135] [] exit_to_usermode_loop+0xfc/0x120 [ 46.989425] [] do_syscall_64+0x364/0x490 [ 46.995106] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 47.002002] 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 c2 c9 fd 4c 89 ea 48 b8 00 [ 47.028876] RIP [] l2tp_session_free+0x11c/0x200 [ 47.035512] RSP [ 47.039109] CR2: 0000000000000080 [ 47.042659] ---[ end trace 0b7778576c256fa8 ]--- [ 47.047436] Kernel panic - not syncing: Fatal exception [ 47.053068] Dumping ftrace buffer: [ 47.056586] (ftrace buffer empty) [ 47.060269] Kernel Offset: disabled [ 47.063883] Rebooting in 86400 seconds..