nacl64.exe and Chrome v69

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Sep 24, 2018, 2:33:45 PM9/24/18
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A client of our extension is having issues with Chrome crashing due to nacl64.exe fault. They get a Windows "Google Chrome has stopped working" message. Interestingly in our test environments we see no nacl64.exe process running. However, as soon as they add the extension in their environment they get the process. A recent update to v69 has started giving them issues when Chrome starts. 

Just looking for some information regarding nacl64.exe and if it should always be running when Chrome is using an extension with an embedded .nexe file. Also, if there are any known issues with Chrome v69 and that executable. Since we don't see the process in our local environments is it something that HAS to be running? Error log below. 

Thanks in advance!

Faulting application name: nacl64.exe, version: 69.0.3497.92, time stamp: 0x5b96fdb5

Faulting module name: nacl64.exe, version: 69.0.3497.92, time stamp: 0x5b96fdb5

Exception code: 0x80000003

Fault offset: 0x00000000000c6aaf

Faulting process id: 0x2790

Faulting application start time: 0x01d44be0417418b0

Faulting application path: C:\Program Files (x86)\Google\Chrome\Application\69.0.3497.92\nacl64.exe

Faulting module path: C:\Program Files (x86)\Google\Chrome\Application\69.0.3497.92\nacl64.exe

Report Id: 807a5ad2-b7d3-11e8-975d-0050560ebead 

Bill Budge

Sep 25, 2018, 2:21:32 PM9/25/18
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Nacl64.exe is the process that runs the instance of a Native Client (nexe) or Portable Native Client (pexe) plugin. Each plugin instance gets its own NaCl64.exe process, so there may be more than one. You can see these processes in Chrome's Task Manager when they're running (in the 3-dot menu, MoreTools/Task Manager) though the name will be displayed as "Native Client Module: <app name>".

A crash in that process could be caused by the untrusted plugin code (nexe) that is part of the extension. The exception code 0x80000003 is for a debugger breakpoint on Windows. It's hard to diagnose why they may be getting that.

Sep 25, 2018, 4:10:42 PM9/25/18
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Thanks so much for the information. I had no clue about the Chrome Task Manager!  I do see the "Native Client module" there. Still seems odd to me that I don't have nacl64.exe running but it is on the client machine. Even odder to me is that nacl64.exe doesn't even exist in the Google/Chrome/Application/[version]/ directory on my (or other testers) machine. 

That said I do see it in the chrome task manager so thanks for that!  I agree though we are assuming something changed in Chrome 69 with regards to writing to or accessing the file system which is now causing the crash. 

Thanks again for the info! Have a great day.


Oct 1, 2018, 11:01:20 PM10/1/18
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AFAIK, only appear if you are running a 32 bit chrome on the 64 bit windows. In this case, because the nacl plugin must run under 64 bit mode, nacl64.exe will be launched. Otherwise (you are using 32 bit chrome under 32 bit windows or using 64 bit chrome under 64 bit windows) there is no need to start the nacl64.exe process.

This is due to a windows kernel restriction, see:!topic/native-client-discuss/n1nPAFVTcyY

32-bit NaCl does not work on 64-bit Windows because Windows effectively disables use of the segment registers, required by the NaCl sandbox.

Oct 2, 2018, 9:59:31 AM10/2/18
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Thank you very much for explaining why I was not seeing nacl64.exe locally. That was indeed the issue. When I switched to 32 bit Chrome I get the nacl64.exe running!  

I really appreciate it.
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