[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.018674] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.492091] random: sshd: uninitialized urandom read (32 bytes read) [ 20.893455] random: sshd: uninitialized urandom read (32 bytes read) [ 21.870979] random: sshd: uninitialized urandom read (32 bytes read) [ 22.009894] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.206' (ECDSA) to the list of known hosts. [ 27.498653] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.697177] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.705455] IP: [] l2tp_session_free+0x11c/0x200 [ 27.711886] PGD 1bc9aa067 [ 27.714536] PUD 1bde7f067 PMD 0 [ 27.718027] [ 27.719657] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.724142] Dumping ftrace buffer: [ 27.727665] (ftrace buffer empty) [ 27.731353] Modules linked in: [ 27.734653] CPU: 0 PID: 3801 Comm: syz-executor844 Not tainted 4.9.113-g47bbcd6 #62 [ 27.742694] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.752046] task: ffff8801b75a4800 task.stack: ffff8801da3b0000 [ 27.758097] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.766969] RSP: 0018:ffff8801da3b7ca0 EFLAGS: 00010246 [ 27.772391] RAX: dffffc0000000000 RBX: ffff8801b5d1db80 RCX: 0000000000000000 [ 27.779657] RDX: 1ffff100398c9210 RSI: ffffffff836bcce1 RDI: ffff8801cc649080 [ 27.786908] RBP: ffff8801da3b7cc0 R08: ffff8801b75a50e8 R09: 0000000000000000 [ 27.794171] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cc648f00 [ 27.801440] R13: ffff8801b5d1db88 R14: 0000000000000000 R15: ffffffff83013be0 [ 27.808698] FS: 0000000001f02880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 27.816907] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.823031] CR2: 0000000000000080 CR3: 00000001bddf0000 CR4: 00000000001606f0 [ 27.831204] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.838464] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.845718] Stack: [ 27.847843] ffff8801b5f08880 ffff8801b5d1db80 ffff8801b5f08c50 ffff8801b5f08b58 [ 27.855855] ffff8801da3b7ce8 ffffffff836c45f2 ffff8801b5f08cc0 ffff8801b5f08880 [ 27.863870] ffffffff836c4520 ffff8801da3b7d20 ffffffff83021095 ffff8801b5f08cc0 [ 27.871921] Call Trace: [ 27.874487] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.881139] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.887436] [] __sk_destruct+0x55/0x590 [ 27.893058] [] ? sock_release+0x1c0/0x1c0 [ 27.898841] [] sk_destruct+0x63/0x80 [ 27.904195] [] __sk_free+0x4f/0x220 [ 27.909455] [] sk_free+0x2b/0x40 [ 27.914456] [] pppol2tp_release+0x239/0x2e0 [ 27.920415] [] sock_release+0x96/0x1c0 [ 27.925928] [] sock_close+0x16/0x20 [ 27.931285] [] __fput+0x263/0x700 [ 27.936365] [] ____fput+0x15/0x20 [ 27.941468] [] task_work_run+0x10c/0x180 [ 27.947167] [] exit_to_usermode_loop+0xfc/0x120 [ 27.953474] [] do_syscall_64+0x364/0x490 [ 27.959162] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.966236] 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 [ 27.993812] RIP [] l2tp_session_free+0x11c/0x200 [ 28.000361] RSP [ 28.003961] CR2: 0000000000000080 [ 28.007656] ---[ end trace 0fc8d2d2aa735764 ]--- [ 28.012400] Kernel panic - not syncing: Fatal exception [ 28.018401] Dumping ftrace buffer: [ 28.021929] (ftrace buffer empty) [ 28.025624] Kernel Offset: disabled [ 28.029227] Rebooting in 86400 seconds..