[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.090552] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 16.715554] random: sshd: uninitialized urandom read (32 bytes read) [ 16.913271] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.778095] random: sshd: uninitialized urandom read (32 bytes read) [ 17.935620] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.15' (ECDSA) to the list of known hosts. [ 23.438743] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.679863] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.688092] IP: [] l2tp_session_free+0x11c/0x200 [ 23.694520] PGD 1bf800067 [ 23.697164] PUD 1c0647067 PMD 0 [ 23.700647] [ 23.702278] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.706750] Dumping ftrace buffer: [ 23.710266] (ftrace buffer empty) [ 23.713953] Modules linked in: [ 23.717248] CPU: 1 PID: 3799 Comm: syz-executor478 Not tainted 4.9.122-g54068d6 #78 [ 23.725021] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.734351] task: ffff8801b9304800 task.stack: ffff8801b5cc0000 [ 23.740382] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.749239] RSP: 0018:ffff8801b5cc7ca0 EFLAGS: 00010246 [ 23.754667] RAX: dffffc0000000000 RBX: ffff8801b5c88780 RCX: 0000000000000000 [ 23.761922] RDX: 1ffff10036efa480 RSI: ffffffff836c39a1 RDI: ffff8801b77d2400 [ 23.769171] RBP: ffff8801b5cc7cc0 R08: ffff8801b93050e8 R09: 0000000000000000 [ 23.776417] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b77d2280 [ 23.783676] R13: ffff8801b5c88788 R14: 0000000000000000 R15: ffffffff83019be0 [ 23.791053] FS: 0000000001a40880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 23.799273] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.805196] CR2: 0000000000000080 CR3: 00000001b933c000 CR4: 00000000001606f0 [ 23.812457] Stack: [ 23.814594] ffff8801b62edd80 ffff8801b5c88780 ffff8801b62ee150 ffff8801b62ee058 [ 23.823561] ffff8801b5cc7ce8 ffffffff836cb2b2 ffff8801b62ee1c0 ffff8801b62edd80 [ 23.831575] ffffffff836cb1e0 ffff8801b5cc7d20 ffffffff830270f5 ffff8801b62ee1c0 [ 23.839591] Call Trace: [ 23.842173] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.848865] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.855167] [] __sk_destruct+0x55/0x590 [ 23.860777] [] ? sock_release+0x1c0/0x1c0 [ 23.866552] [] sk_destruct+0x63/0x80 [ 23.871894] [] __sk_free+0x4f/0x220 [ 23.877154] [] sk_free+0x2b/0x40 [ 23.882151] [] pppol2tp_release+0x239/0x2e0 [ 23.888100] [] sock_release+0x96/0x1c0 [ 23.893614] [] sock_close+0x16/0x20 [ 23.898871] [] __fput+0x263/0x700 [ 23.903955] [] ____fput+0x15/0x20 [ 23.909037] [] task_work_run+0x10c/0x180 [ 23.914727] [] exit_to_usermode_loop+0xfc/0x120 [ 23.921026] [] do_syscall_64+0x364/0x490 [ 23.926716] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.933615] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 23.960718] RIP [] l2tp_session_free+0x11c/0x200 [ 23.967238] RSP [ 23.970840] CR2: 0000000000000080 [ 23.974806] ---[ end trace 8ce8109ca4d1c7a9 ]--- [ 23.979557] Kernel panic - not syncing: Fatal exception [ 23.985368] Dumping ftrace buffer: [ 23.988898] (ftrace buffer empty) [ 23.992588] Kernel Offset: disabled [ 23.996358] Rebooting in 86400 seconds..