[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.996280] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.451598] random: sshd: uninitialized urandom read (32 bytes read) [ 21.975360] random: sshd: uninitialized urandom read (32 bytes read) [ 22.952214] random: sshd: uninitialized urandom read (32 bytes read) [ 23.080580] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.195' (ECDSA) to the list of known hosts. [ 28.667409] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 28.870516] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 28.878713] IP: [] l2tp_session_free+0x11c/0x200 [ 28.885163] PGD 1c57ae067 [ 28.887931] PUD 1c1942067 PMD 0 [ 28.891402] [ 28.893017] Oops: 0002 [#1] PREEMPT SMP KASAN [ 28.897492] Dumping ftrace buffer: [ 28.900998] (ftrace buffer empty) [ 28.904684] Modules linked in: [ 28.908003] CPU: 0 PID: 3806 Comm: syz-executor904 Not tainted 4.9.116-g0137ea2 #70 [ 28.915785] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.925118] task: ffff8801b73bb000 task.stack: ffff8801b5030000 [ 28.931154] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.940008] RSP: 0018:ffff8801b5037ca0 EFLAGS: 00010246 [ 28.945437] RAX: dffffc0000000000 RBX: ffff8801c8bd5680 RCX: 0000000000000000 [ 28.952678] RDX: 1ffff1003962c920 RSI: ffffffff836be8f1 RDI: ffff8801cb164900 [ 28.959932] RBP: ffff8801b5037cc0 R08: ffff8801b73bb8e8 R09: 0000000000000000 [ 28.967174] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb164780 [ 28.974418] R13: ffff8801c8bd5688 R14: 0000000000000000 R15: ffffffff83014be0 [ 28.981664] FS: 00000000010db880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 28.989959] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.995813] CR2: 0000000000000080 CR3: 00000001c2be9000 CR4: 00000000001606f0 [ 29.003063] Stack: [ 29.005178] ffff8801b9af3b80 ffff8801c8bd5680 ffff8801b9af3f50 ffff8801b9af3e58 [ 29.013174] ffff8801b5037ce8 ffffffff836c6202 ffff8801b9af3fc0 ffff8801b9af3b80 [ 29.021173] ffffffff836c6130 ffff8801b5037d20 ffffffff83022095 ffff8801b9af3fc0 [ 29.029180] Call Trace: [ 29.031748] [] pppol2tp_session_destruct+0xd2/0x110 [ 29.038407] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 29.044723] [] __sk_destruct+0x55/0x590 [ 29.050321] [] ? sock_release+0x1c0/0x1c0 [ 29.056092] [] sk_destruct+0x63/0x80 [ 29.061426] [] __sk_free+0x4f/0x220 [ 29.068053] [] sk_free+0x2b/0x40 [ 29.073051] [] pppol2tp_release+0x239/0x2e0 [ 29.079007] [] sock_release+0x96/0x1c0 [ 29.084517] [] sock_close+0x16/0x20 [ 29.089766] [] __fput+0x263/0x700 [ 29.094858] [] ____fput+0x15/0x20 [ 29.099934] [] task_work_run+0x10c/0x180 [ 29.105617] [] exit_to_usermode_loop+0xfc/0x120 [ 29.111923] [] do_syscall_64+0x364/0x490 [ 29.117629] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 29.124541] 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 [ 29.151520] RIP [] l2tp_session_free+0x11c/0x200 [ 29.158021] RSP [ 29.161619] CR2: 0000000000000080 [ 29.165330] ---[ end trace 75f329d7f7572041 ]--- [ 29.170107] Kernel panic - not syncing: Fatal exception [ 29.175821] Dumping ftrace buffer: [ 29.179349] (ftrace buffer empty) [ 29.183049] Kernel Offset: disabled [ 29.186672] Rebooting in 86400 seconds..