[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.401430] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.534675] random: sshd: uninitialized urandom read (32 bytes read) [ 18.874162] random: sshd: uninitialized urandom read (32 bytes read) [ 19.844158] random: sshd: uninitialized urandom read (32 bytes read) [ 19.990117] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.48' (ECDSA) to the list of known hosts. [ 25.460218] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.687607] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.695921] IP: [] l2tp_session_free+0x11c/0x200 [ 25.702365] PGD 1b7961067 [ 25.705008] PUD 1b7eb0067 PMD 0 [ 25.708499] [ 25.710140] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.714615] Dumping ftrace buffer: [ 25.718175] (ftrace buffer empty) [ 25.721882] Modules linked in: [ 25.725190] CPU: 1 PID: 3803 Comm: syz-executor821 Not tainted 4.9.113-g47bbcd6 #10 [ 25.732959] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.742301] task: ffff8801b8f4e000 task.stack: ffff8801d9400000 [ 25.748334] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.757219] RSP: 0018:ffff8801d9407ca0 EFLAGS: 00010246 [ 25.762669] RAX: dffffc0000000000 RBX: ffff8801b6587900 RCX: 0000000000000000 [ 25.769930] RDX: 1ffff10036c9c6b0 RSI: ffffffff836bcce1 RDI: ffff8801b64e3580 [ 25.777195] RBP: ffff8801d9407cc0 R08: ffff8801b8f4e8e8 R09: 0000000000000000 [ 25.784464] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b64e3400 [ 25.791740] R13: ffff8801b6587908 R14: 0000000000000000 R15: ffffffff83013be0 [ 25.799006] FS: 0000000001fa0880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 25.807248] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.813124] CR2: 0000000000000080 CR3: 00000001bac20000 CR4: 00000000001606f0 [ 25.820389] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.827661] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.834925] Stack: [ 25.837082] ffff8801b6773b80 ffff8801b6587900 ffff8801b6773f50 ffff8801b6773e58 [ 25.845115] ffff8801d9407ce8 ffffffff836c45f2 ffff8801b6773fc0 ffff8801b6773b80 [ 25.853135] ffffffff836c4520 ffff8801d9407d20 ffffffff83021095 ffff8801b6773fc0 [ 25.861162] Call Trace: [ 25.863772] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.870442] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.876767] [] __sk_destruct+0x55/0x590 [ 25.882397] [] ? sock_release+0x1c0/0x1c0 [ 25.888197] [] sk_destruct+0x63/0x80 [ 25.893561] [] __sk_free+0x4f/0x220 [ 25.898827] [] sk_free+0x2b/0x40 [ 25.903834] [] pppol2tp_release+0x239/0x2e0 [ 25.909802] [] sock_release+0x96/0x1c0 [ 25.915331] [] sock_close+0x16/0x20 [ 25.920594] [] __fput+0x263/0x700 [ 25.925697] [] ____fput+0x15/0x20 [ 25.930799] [] task_work_run+0x10c/0x180 [ 25.936499] [] exit_to_usermode_loop+0xfc/0x120 [ 25.942803] [] do_syscall_64+0x364/0x490 [ 25.948533] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.955440] 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 55 1d ca fd 4c 89 ea 48 b8 00 [ 25.982449] RIP [] l2tp_session_free+0x11c/0x200 [ 25.988965] RSP [ 25.992564] CR2: 0000000000000080 [ 25.996076] ---[ end trace 3fe374b7019b7deb ]--- [ 26.000852] Kernel panic - not syncing: Fatal exception [ 26.006741] Dumping ftrace buffer: [ 26.010266] (ftrace buffer empty) [ 26.013964] Kernel Offset: disabled [ 26.017578] Rebooting in 86400 seconds..