[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.234979] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.809495] random: sshd: uninitialized urandom read (32 bytes read) [ 22.215464] random: sshd: uninitialized urandom read (32 bytes read) [ 22.580555] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.21' (ECDSA) to the list of known hosts. [ 28.126753] urandom_read: 1 callbacks suppressed [ 28.126756] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 28.328789] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 28.337020] IP: [] l2tp_session_free+0x11c/0x200 [ 28.343447] PGD 1c5b14067 [ 28.346088] PUD 1c6749067 PMD 0 [ 28.349565] [ 28.351184] Oops: 0002 [#1] PREEMPT SMP KASAN [ 28.355661] Dumping ftrace buffer: [ 28.359172] (ftrace buffer empty) [ 28.362871] Modules linked in: [ 28.366171] CPU: 1 PID: 3630 Comm: syz-executor722 Not tainted 4.9.117-g8b21e85 #19 [ 28.373935] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.383363] task: ffff8801c6330000 task.stack: ffff8801c5550000 [ 28.389400] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.398251] RSP: 0018:ffff8801c5557ca0 EFLAGS: 00010246 [ 28.403673] RAX: dffffc0000000000 RBX: ffff8801c5908780 RCX: 0000000000000000 [ 28.410919] RDX: 1ffff10038b42fa0 RSI: ffffffff836bf8f1 RDI: ffff8801c5a17d00 [ 28.418170] RBP: ffff8801c5557cc0 R08: ffff8801c63308e8 R09: 0000000000000000 [ 28.425417] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c5a17b80 [ 28.432666] R13: ffff8801c5908788 R14: 0000000000000000 R15: ffffffff83015be0 [ 28.440001] FS: 0000000001070880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 28.448209] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.454067] CR2: 0000000000000080 CR3: 00000001cb01a000 CR4: 00000000001606f0 [ 28.461324] Stack: [ 28.463447] ffff8801c5ea0880 ffff8801c5908780 ffff8801c5ea0c50 ffff8801c5ea0b58 [ 28.471434] ffff8801c5557ce8 ffffffff836c7202 ffff8801c5ea0cc0 ffff8801c5ea0880 [ 28.479456] ffffffff836c7130 ffff8801c5557d20 ffffffff83023095 ffff8801c5ea0cc0 [ 28.487471] Call Trace: [ 28.490051] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.496693] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.502992] [] __sk_destruct+0x55/0x590 [ 28.508592] [] ? sock_release+0x1c0/0x1c0 [ 28.514362] [] sk_destruct+0x63/0x80 [ 28.519720] [] __sk_free+0x4f/0x220 [ 28.524987] [] sk_free+0x2b/0x40 [ 28.529985] [] pppol2tp_release+0x239/0x2e0 [ 28.535936] [] sock_release+0x96/0x1c0 [ 28.541454] [] sock_close+0x16/0x20 [ 28.546722] [] __fput+0x263/0x700 [ 28.551835] [] ____fput+0x15/0x20 [ 28.556951] [] task_work_run+0x10c/0x180 [ 28.562638] [] exit_to_usermode_loop+0xfc/0x120 [ 28.568925] [] do_syscall_64+0x364/0x490 [ 28.574615] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.581510] 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 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 28.608335] RIP [] l2tp_session_free+0x11c/0x200 [ 28.614835] RSP [ 28.618434] CR2: 0000000000000080 [ 28.622163] ---[ end trace 45c4799ba00f2e63 ]--- [ 28.626901] Kernel panic - not syncing: Fatal exception [ 28.632503] Dumping ftrace buffer: [ 28.636026] (ftrace buffer empty) [ 28.639715] Kernel Offset: disabled [ 28.643341] Rebooting in 86400 seconds..