[....] 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[ 13.542027] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.685361] random: sshd: uninitialized urandom read (32 bytes read) [ 18.027981] random: sshd: uninitialized urandom read (32 bytes read) [ 18.534575] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.30' (ECDSA) to the list of known hosts. [ 24.298629] urandom_read: 1 callbacks suppressed [ 24.298633] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.526094] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.534564] IP: [] l2tp_session_free+0x11c/0x200 [ 24.540988] PGD 1c645f067 [ 24.543633] PUD 1c9ff9067 PMD 0 [ 24.547114] [ 24.548846] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.553322] Dumping ftrace buffer: [ 24.556838] (ftrace buffer empty) [ 24.560535] Modules linked in: [ 24.563852] CPU: 1 PID: 3777 Comm: syz-executor235 Not tainted 4.9.119-g9dc978d #75 [ 24.571634] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.580985] task: ffff8801bcdce000 task.stack: ffff8801ba638000 [ 24.587301] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.596169] RSP: 0018:ffff8801ba63fca0 EFLAGS: 00010246 [ 24.601594] RAX: dffffc0000000000 RBX: ffff8801bb232a00 RCX: 0000000000000000 [ 24.608905] RDX: 1ffff100376007a0 RSI: ffffffff836bf9a1 RDI: ffff8801bb003d00 [ 24.616224] RBP: ffff8801ba63fcc0 R08: ffff8801bcdce8e8 R09: 0000000000000000 [ 24.623479] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bb003b80 [ 24.630847] R13: ffff8801bb232a08 R14: 0000000000000000 R15: ffffffff83015be0 [ 24.638101] FS: 00000000017e9880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 24.646415] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.652286] CR2: 0000000000000080 CR3: 00000001bce96000 CR4: 00000000001606f0 [ 24.659610] Stack: [ 24.661746] ffff8801ba628000 ffff8801bb232a00 ffff8801ba6283d0 ffff8801ba6282d8 [ 24.669766] ffff8801ba63fce8 ffffffff836c72b2 ffff8801ba628440 ffff8801ba628000 [ 24.677778] ffffffff836c71e0 ffff8801ba63fd20 ffffffff830230f5 ffff8801ba628440 [ 24.685861] Call Trace: [ 24.688440] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.695220] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.701637] [] __sk_destruct+0x55/0x590 [ 24.707241] [] ? sock_release+0x1c0/0x1c0 [ 24.713017] [] sk_destruct+0x63/0x80 [ 24.718360] [] __sk_free+0x4f/0x220 [ 24.723617] [] sk_free+0x2b/0x40 [ 24.728616] [] pppol2tp_release+0x239/0x2e0 [ 24.734566] [] sock_release+0x96/0x1c0 [ 24.740179] [] sock_close+0x16/0x20 [ 24.745461] [] __fput+0x263/0x700 [ 24.750550] [] ____fput+0x15/0x20 [ 24.755634] [] task_work_run+0x10c/0x180 [ 24.761323] [] exit_to_usermode_loop+0xfc/0x120 [ 24.767616] [] do_syscall_64+0x364/0x490 [ 24.773305] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.780203] 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 f0 c9 fd 4c 89 ea 48 b8 00 [ 24.807571] RIP [] l2tp_session_free+0x11c/0x200 [ 24.814202] RSP [ 24.817806] CR2: 0000000000000080 [ 24.821309] ---[ end trace 4c67697b34b481fa ]--- [ 24.826093] Kernel panic - not syncing: Fatal exception [ 24.831772] Dumping ftrace buffer: [ 24.835298] (ftrace buffer empty) [ 24.838987] Kernel Offset: disabled [ 24.842591] Rebooting in 86400 seconds..