[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 11.544893] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.242617] random: sshd: uninitialized urandom read (32 bytes read) [ 16.552770] random: sshd: uninitialized urandom read (32 bytes read) [ 17.332550] random: sshd: uninitialized urandom read (32 bytes read) [ 29.705157] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.24' (ECDSA) to the list of known hosts. [ 35.088709] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 35.310877] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 35.319099] IP: [<ffffffff836bcd0c>] l2tp_session_free+0x11c/0x200 [ 35.325521] PGD 1c5fd8067 [ 35.328167] PUD 1c7ad7067 PMD 0 [ 35.331640] [ 35.333259] Oops: 0002 [#1] PREEMPT SMP KASAN [ 35.337739] Dumping ftrace buffer: [ 35.341250] (ftrace buffer empty) [ 35.344934] Modules linked in: [ 35.348223] CPU: 1 PID: 3740 Comm: syz-executor166 Not tainted 4.9.113-g47bbcd6 #62 [ 35.355987] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 35.365314] task: ffff8801bfaee000 task.stack: ffff8801bde88000 [ 35.371338] RIP: 0010:[<ffffffff836bcd0c>] [<ffffffff836bcd0c>] l2tp_session_free+0x11c/0x200 [ 35.380202] RSP: 0018:ffff8801bde8fca0 EFLAGS: 00010246 [ 35.385642] RAX: dffffc0000000000 RBX: ffff8801be3b7400 RCX: 0000000000000000 [ 35.392886] RDX: 1ffff10037bcb5c0 RSI: ffffffff836bcce1 RDI: ffff8801bde5ae00 [ 35.400128] RBP: ffff8801bde8fcc0 R08: ffff8801bfaee8e8 R09: 0000000000000000 [ 35.407371] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bde5ac80 [ 35.414616] R13: ffff8801be3b7408 R14: 0000000000000000 R15: ffffffff83013be0 [ 35.421863] FS: 0000000002407880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 35.430059] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 35.435911] CR2: 0000000000000080 CR3: 00000001c8479000 CR4: 00000000001606f0 [ 35.443157] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 35.450401] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 35.457646] Stack: [ 35.459768] ffff8801bf18c400 ffff8801be3b7400 ffff8801bf18c7d0 ffff8801bf18c6d8 [ 35.467758] ffff8801bde8fce8 ffffffff836c45f2 ffff8801bf18c840 ffff8801bf18c400 [ 35.475743] ffffffff836c4520 ffff8801bde8fd20 ffffffff83021095 ffff8801bf18c840 [ 35.483737] Call Trace: [ 35.486302] [<ffffffff836c45f2>] pppol2tp_session_destruct+0xd2/0x110 [ 35.492941] [<ffffffff836c4520>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 35.499254] [<ffffffff83021095>] __sk_destruct+0x55/0x590 [ 35.504850] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 35.510624] [<ffffffff83028b23>] sk_destruct+0x63/0x80 [ 35.516045] [<ffffffff83028b8f>] __sk_free+0x4f/0x220 [ 35.521302] [<ffffffff83028d8b>] sk_free+0x2b/0x40 [ 35.526301] [<ffffffff836c78f9>] pppol2tp_release+0x239/0x2e0 [ 35.532244] [<ffffffff83013ab6>] sock_release+0x96/0x1c0 [ 35.537752] [<ffffffff83013bf6>] sock_close+0x16/0x20 [ 35.542999] [<ffffffff815782e3>] __fput+0x263/0x700 [ 35.548073] [<ffffffff81578805>] ____fput+0x15/0x20 [ 35.553150] [<ffffffff8119838c>] task_work_run+0x10c/0x180 [ 35.558920] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 35.565210] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 35.570894] [<ffffffff839f9f93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 35.577788] 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 <f0> 41 ff 8e 80 00 00 00 74 69 e8 55 1d ca fd 4c 89 ea 48 b8 00 [ 35.604565] RIP [<ffffffff836bcd0c>] l2tp_session_free+0x11c/0x200 [ 35.611075] RSP <ffff8801bde8fca0> [ 35.614672] CR2: 0000000000000080 [ 35.618204] ---[ end trace e354f934227f47f8 ]--- [ 35.622954] Kernel panic - not syncing: Fatal exception [ 35.628678] Dumping ftrace buffer: [ 35.632191] (ftrace buffer empty) [ 35.635879] Kernel Offset: disabled [ 35.639491] Rebooting in 86400 seconds..