[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.478371] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.846896] random: sshd: uninitialized urandom read (32 bytes read) [ 17.108065] random: sshd: uninitialized urandom read (32 bytes read) [ 18.046776] random: sshd: uninitialized urandom read (32 bytes read) [ 42.330561] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.50' (ECDSA) to the list of known hosts. [ 47.789311] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 48.012098] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 48.020369] IP: [] l2tp_session_free+0x11c/0x200 [ 48.026802] PGD 1bbbb9067 [ 48.029455] PUD 1bbb8f067 PMD 0 [ 48.032942] [ 48.034569] Oops: 0002 [#1] PREEMPT SMP KASAN [ 48.039045] Dumping ftrace buffer: [ 48.042567] (ftrace buffer empty) [ 48.046267] Modules linked in: [ 48.049583] CPU: 1 PID: 3821 Comm: syz-executor257 Not tainted 4.9.113-g90e7a90 #68 [ 48.057353] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 48.066700] task: ffff8801b92bb000 task.stack: ffff8801d8ca8000 [ 48.072749] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 48.081632] RSP: 0018:ffff8801d8cafca0 EFLAGS: 00010246 [ 48.087053] RAX: dffffc0000000000 RBX: ffff8801c9197b80 RCX: 0000000000000000 [ 48.094307] RDX: 1ffff10036b5fcd0 RSI: ffffffff836bdee1 RDI: ffff8801b5afe680 [ 48.101552] RBP: ffff8801d8cafcc0 R08: ffff8801b92bb8e8 R09: 0000000000000000 [ 48.108797] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5afe500 [ 48.116040] R13: ffff8801c9197b88 R14: 0000000000000000 R15: ffffffff83014be0 [ 48.123304] FS: 0000000001911880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 48.131503] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 48.137368] CR2: 0000000000000080 CR3: 00000001bcf9c000 CR4: 00000000001606f0 [ 48.144896] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 48.152141] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 48.159404] Stack: [ 48.161536] ffff8801b7faf700 ffff8801c9197b80 ffff8801b7fafad0 ffff8801b7faf9d8 [ 48.169763] ffff8801d8cafce8 ffffffff836c57f2 ffff8801b7fafb40 ffff8801b7faf700 [ 48.177773] ffffffff836c5720 ffff8801d8cafd20 ffffffff83022095 ffff8801b7fafb40 [ 48.185768] Call Trace: [ 48.188344] [] pppol2tp_session_destruct+0xd2/0x110 [ 48.194983] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 48.201274] [] __sk_destruct+0x55/0x590 [ 48.206882] [] ? sock_release+0x1c0/0x1c0 [ 48.212650] [] sk_destruct+0x63/0x80 [ 48.218073] [] __sk_free+0x4f/0x220 [ 48.223331] [] sk_free+0x2b/0x40 [ 48.228320] [] pppol2tp_release+0x239/0x2e0 [ 48.234272] [] sock_release+0x96/0x1c0 [ 48.239795] [] sock_close+0x16/0x20 [ 48.245047] [] __fput+0x263/0x700 [ 48.250125] [] ____fput+0x15/0x20 [ 48.255214] [] task_work_run+0x10c/0x180 [ 48.260913] [] exit_to_usermode_loop+0xfc/0x120 [ 48.267208] [] do_syscall_64+0x364/0x490 [ 48.272891] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 48.279786] 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 0b ca fd 4c 89 ea 48 b8 00 [ 48.306841] RIP [] l2tp_session_free+0x11c/0x200 [ 48.313351] RSP [ 48.316948] CR2: 0000000000000080 [ 48.320494] ---[ end trace d02678aa50bad874 ]--- [ 48.325253] Kernel panic - not syncing: Fatal exception [ 48.331002] Dumping ftrace buffer: [ 48.334515] (ftrace buffer empty) [ 48.338204] Kernel Offset: disabled [ 48.341803] Rebooting in 86400 seconds..