[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.731534] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.049225] random: sshd: uninitialized urandom read (32 bytes read) [ 20.495717] random: sshd: uninitialized urandom read (32 bytes read) [ 20.997584] random: sshd: uninitialized urandom read (32 bytes read) [ 21.137942] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.25' (ECDSA) to the list of known hosts. [ 26.566041] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.776937] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.785172] IP: [] l2tp_session_free+0x11c/0x200 [ 26.791594] PGD 1c71f6067 [ 26.794245] PUD 1c705b067 PMD 0 [ 26.797734] [ 26.799377] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.803854] Dumping ftrace buffer: [ 26.807372] (ftrace buffer empty) [ 26.811068] Modules linked in: [ 26.814389] CPU: 1 PID: 3796 Comm: syz-executor112 Not tainted 4.9.118-g856452b #21 [ 26.822158] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.831507] task: ffff8801b7066000 task.stack: ffff8801d94a8000 [ 26.837537] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 26.846402] RSP: 0018:ffff8801d94afca0 EFLAGS: 00010246 [ 26.851825] RAX: dffffc0000000000 RBX: ffff8801c803a500 RCX: 0000000000000000 [ 26.859073] RDX: 1ffff10036f62c30 RSI: ffffffff836bf781 RDI: ffff8801b7b16180 [ 26.866329] RBP: ffff8801d94afcc0 R08: ffff8801b70668e8 R09: 0000000000000000 [ 26.873577] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b7b16000 [ 26.880828] R13: ffff8801c803a508 R14: 0000000000000000 R15: ffffffff83015be0 [ 26.888093] FS: 00000000015bc880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 26.896295] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.902153] CR2: 0000000000000080 CR3: 00000001c2d3d000 CR4: 00000000001606f0 [ 26.909397] Stack: [ 26.911520] ffff8801b6eba200 ffff8801c803a500 ffff8801b6eba5d0 ffff8801b6eba4d8 [ 26.919527] ffff8801d94afce8 ffffffff836c7092 ffff8801b6eba640 ffff8801b6eba200 [ 26.927531] ffffffff836c6fc0 ffff8801d94afd20 ffffffff830230f5 ffff8801b6eba640 [ 26.935527] Call Trace: [ 26.938103] [] pppol2tp_session_destruct+0xd2/0x110 [ 26.944742] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.951051] [] __sk_destruct+0x55/0x590 [ 26.956653] [] ? sock_release+0x1c0/0x1c0 [ 26.962427] [] sk_destruct+0x63/0x80 [ 26.967767] [] __sk_free+0x4f/0x220 [ 26.973019] [] sk_free+0x2b/0x40 [ 26.978009] [] pppol2tp_release+0x239/0x2e0 [ 26.983957] [] sock_release+0x96/0x1c0 [ 26.989470] [] sock_close+0x16/0x20 [ 26.994725] [] __fput+0x263/0x700 [ 26.999803] [] ____fput+0x15/0x20 [ 27.004886] [] task_work_run+0x10c/0x180 [ 27.010573] [] exit_to_usermode_loop+0xfc/0x120 [ 27.016869] [] do_syscall_64+0x364/0x490 [ 27.022556] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.029463] 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 f5 f2 c9 fd 4c 89 ea 48 b8 00 [ 27.056600] RIP [] l2tp_session_free+0x11c/0x200 [ 27.063100] RSP [ 27.066713] CR2: 0000000000000080 [ 27.071742] ---[ end trace 94ee08d57c475d58 ]--- [ 27.078037] Kernel panic - not syncing: Fatal exception [ 27.083699] Dumping ftrace buffer: [ 27.087217] (ftrace buffer empty) [ 27.090902] Kernel Offset: disabled [ 27.094503] Rebooting in 86400 seconds..