[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.125658] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.548828] random: sshd: uninitialized urandom read (32 bytes read) [ 26.959268] random: sshd: uninitialized urandom read (32 bytes read) [ 27.551253] random: sshd: uninitialized urandom read (32 bytes read) [ 27.677325] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.51' (ECDSA) to the list of known hosts. [ 33.102706] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 33.293550] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 33.301785] IP: [] l2tp_session_free+0x11c/0x200 [ 33.308216] PGD 1b67eb067 [ 33.310856] PUD 1b5e04067 PMD 0 [ 33.314337] [ 33.315961] Oops: 0002 [#1] PREEMPT SMP KASAN [ 33.320430] Dumping ftrace buffer: [ 33.323944] (ftrace buffer empty) [ 33.327631] Modules linked in: [ 33.330925] CPU: 1 PID: 3801 Comm: syz-executor575 Not tainted 4.9.116-g0137ea2 #18 [ 33.338693] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.348032] task: ffff8801b7df6000 task.stack: ffff8801bf328000 [ 33.354153] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 33.363109] RSP: 0018:ffff8801bf32fca0 EFLAGS: 00010246 [ 33.368536] RAX: dffffc0000000000 RBX: ffff8801b736d680 RCX: 0000000000000000 [ 33.375784] RDX: 1ffff10036e74d20 RSI: ffffffff836be8f1 RDI: ffff8801b73a6900 [ 33.383027] RBP: ffff8801bf32fcc0 R08: ffff8801b7df68e8 R09: 0000000000000000 [ 33.390284] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b73a6780 [ 33.397527] R13: ffff8801b736d688 R14: 0000000000000000 R15: ffffffff83014be0 [ 33.404779] FS: 0000000001ab3880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 33.412981] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 33.418839] CR2: 0000000000000080 CR3: 00000001b7e9d000 CR4: 00000000001606f0 [ 33.426096] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 33.433353] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 33.440598] Stack: [ 33.442735] ffff8801da362a80 ffff8801b736d680 ffff8801da362e50 ffff8801da362d58 [ 33.450745] ffff8801bf32fce8 ffffffff836c6202 ffff8801da362ec0 ffff8801da362a80 [ 33.458747] ffffffff836c6130 ffff8801bf32fd20 ffffffff83022095 ffff8801da362ec0 [ 33.466764] Call Trace: [ 33.469331] [] pppol2tp_session_destruct+0xd2/0x110 [ 33.475970] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 33.482263] [] __sk_destruct+0x55/0x590 [ 33.487874] [] ? sock_release+0x1c0/0x1c0 [ 33.493657] [] sk_destruct+0x63/0x80 [ 33.499000] [] __sk_free+0x4f/0x220 [ 33.504257] [] sk_free+0x2b/0x40 [ 33.509254] [] pppol2tp_release+0x239/0x2e0 [ 33.515204] [] sock_release+0x96/0x1c0 [ 33.520718] [] sock_close+0x16/0x20 [ 33.525971] [] __fput+0x263/0x700 [ 33.531050] [] ____fput+0x15/0x20 [ 33.536130] [] task_work_run+0x10c/0x180 [ 33.541816] [] exit_to_usermode_loop+0xfc/0x120 [ 33.548108] [] do_syscall_64+0x364/0x490 [ 33.553795] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 33.560691] 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 65 01 ca fd 4c 89 ea 48 b8 00 [ 33.587768] RIP [] l2tp_session_free+0x11c/0x200 [ 33.594278] RSP [ 33.597876] CR2: 0000000000000080 [ 33.601879] ---[ end trace a2010f94957dc490 ]--- [ 33.606641] Kernel panic - not syncing: Fatal exception [ 33.612389] Dumping ftrace buffer: [ 33.615910] (ftrace buffer empty) [ 33.619598] Kernel Offset: disabled [ 33.623209] Rebooting in 86400 seconds..