Asterisk/FreePBX Crashing and FRACK! Errors

Running FreePBX and Asterisk 13.17.0

I have previously posted about this issue here:

Host: Dell R720 with 2x Xeon E5-2620 2.00GHz (6 Core) and 64GB RAM DDR3 ECC), local PERC storage.

Hypervisor: Proxmox 4.4-1.

Network: using onboard Quad NIC. Bridge “vmbr0” points to “bond0” as the bridge port, and bond0 has eth0 and eth1 in it in “active-backup” mode, each going to one of our two core switches. Using Cisco 3560G. Switch ports are in trunk mode, with native vlan set to our management vlan. VMs are tagged to our public facing vlan, for direct internet access.

VMs are running FreePBX/Asterisk versions mentioned above. Each have 4GB RAM fixed with ballooning disabled, 4 cores (2 sockets, 2 cores; have tried with NUMA enabled and disabled) with type “Default (kvm64)”, NIC using E1000 model, vdisk is 300G presented as ide0 as a raw image on a local LVM-Thin volume.

Endpoints: All endpoints are NAT’d. We use TCP for SIP with an obscure port (not 5060 or near that). RTP traffic on our VSP’s required port range is allowed as well. All other traffic is dropped per the FreePBX firewall.

In summary, what is happening is that we get a bunch of errors like this:

[2017-09-28 02:05:18] ERROR[7061] astobj2.c: FRACK!, Failed assertion bad magic number 0x0 for object 0x3e7c690 (0)
[2017-09-28 02:05:24] ERROR[6934] astobj2.c: FRACK!, Failed assertion bad magic number 0x0 for object 0x3e7c690 (0)
[2017-09-28 02:05:28] ERROR[7107] astobj2.c: FRACK!, Failed assertion bad magic number 0x0 for object 0x3e7c690 (0)

and right before and after, we have most of our peers go unreachable. Sometime Asterisk will crash afterwards, sometimes not.

The issue happens intermittently, but seems to happen more frequently on the VMs that have more peers/endpoints (100+). I don’t think we’ve had it happen on any VMs that had less than 100 peers/endpoints.

We recently chopped a server that had about 130 endpoints into two of 110 and 20. More accurately, we moved 110 off server A to server B, leaving 20 on server B. Before that move, we were experiencing FRACK! errors every day (anywhere from 20-300, usually all within a 20 minute window or so). Once the 110 were moved to server B, server A has never again had FRACK! errors or asterisk crashes. Server B however is having them now, just much less often then when all 130 endpoints were on server A. My assumption for that is due to the slightly lower endpoint total on the VM.

This morning was one of those instances. We had 193 errors, identical to the three I posted above (minus the ERROR[number] being different). AND, we had a crash afterwards. Here is the backtrace:

So I come to you, the asterisk community, for help. I first posted on the FreePBX forum, and was directed here.

I understand this may point to a memory issue, but what is strange is that the Dell iDrac log doesn’t show any memory errors in it. Perhaps there are errors but iDrac just isn’t seeing them to report them. I’m hoping someone out there can parse through the backtrace and give me a clear answer to what the problem is. Thanks in advance.

You have memory corruption. If you are lucky, there will be an earlier error, or warning, that gives a clue as to what caused the corruption. Otherwise debugging this will be different.

Thank you for the response. So I’m in a tough spot troubleshooting wise. This is a production server with several VMs running on it. Would you suggest swapping out the ram in it? Or do you think the memory corruption is something at the software level regardless of what memory is inside? Or is there just not enough information at this point to tell?

Memory corruption is normally the result of software errors. The problem with it is the symptoms can be delayed relative to the original cause.

Okay thanks. Any suggestions on the next best step troubleshooting this?

Any ideas on best next steps troubleshooting anyone?

You either have to work out what event triggers the crash, or you need to look at a crash dump and see if you can identify what the corrupted data was over-written with. The latter is very difficult.

Although, my recent experience is that such faults are software related, it might be worth running a memory diagnostic, assuming you have a standby machine, or a time of day that can be used for maintenance.

Thanks David. I pastbin’d the backtrace of the dump (above), but the dump itself was too big.

Here’s a link to the dump:

Is our dump something you would be willing to look at?

The dump will not make sense without the exact same binaries, including libraries, that you used. The chances of recognizing what is causing the corruption is way too low to make it worth my time looking.

Understood. So if you were us, what would you do, assuming the memory is not corrupt? We have done fresh installs from the FreePBX 13 distro, fully updated, and are still having this problem.

I would look for errors about failed locks.

Actually, rebuilding with thread debugging may give you more messages.

Where I have debugged this sort of thing, it has been from a developer perspective and involves quite a lot of knowledge of how the code works.

Would these failed lock messages be in the asterisk logs or?

Can you give me an example of what I’m looking for?

See above message? Also, we get a lot of Serious Network errors on these servers like this:

[2017-10-05 06:06:33] ERROR[7418] chan_sip.c: Serious Network Trouble; __sip_xmit returns error for pkt data
[2017-10-05 06:06:47] ERROR[7418] chan_sip.c: Serious Network Trouble; __sip_xmit returns error for pkt data
[2017-10-05 07:39:11] ERROR[8830] chan_sip.c: Serious Network Trouble; __sip_xmit returns error for pkt data

I’ve noticed they only come up on servers that we have TCP enabled for SIP, and are using an obscure port number (for security). Are there any known issue with using TCP for SIP? We have both TCP and UDP enabled, but only our VSP communicates with us via UDP.


Do you think the cause of our FRACK Errors and crashing are related to these Serious Network Trouble Errors?

They are unlikely to be related.

Hi Dave, I just found this:

It says: In case you wonder why on earth is asterisk failing with a segmentation fault after a fresh install (compilation by hand from sources) – and you happen to run it in a KVM virtual machine – then the answer is pretty easy: make sure you run make menuconfig before you start the compilation and remove the compilation flag called “BUILD NATIVE”. Once you do that asterisk will run normally.

Ever hear about needed to do this with KVM VMs? I know nothing about compiling asterisk for the FreePBX distro, but if someone thinks this is a good lead, I’ll do it.

Broken VMs normally cause an illegal instruction fault, not a segmentation fault. The VM mis-describes the capabilities or the virtual CPU and gcc compiles code that uses instructions that are on the CPU described but not on the real/emulated one.

So where does this leave me?