Tor Browser 7.5 is not working on Windows Vista 64bit

We have some users on the blog complaining about Tor Browser 7.5 being broken on Windows Vista 64bit. See, for instance:https://blog.torproject.org/comment/273815#comment-273815

The error ("TypeError: frameLoader.tabParent is null") might indicate that our enabled sandboxing is breaking things for them.

added TorBrowserTeam201803R component::applications/tor browser ff60-esr-will-have owner::pospeselr priority::high resolution::fixed severity::major status::closed type::defect labels

FWIW: Windows Vista is EOL for almost a year now. Might still be worth trying to understand what the issue is and fixing it if it is easy.

#25130 (moved) also got closed as a duplicate.

#25130 (moved) is a duplicate.

jllover: I assume this issue shows up due to us enabling sandboxing support for Windows with 7.5. Alas, this did not get caught in our testing and seems to be only affecting Windows Vista which is not supported anymore from Microsoft.

Not sure if you still can open new tabs but if so, open one and enter about:config in the URL bar and then you can test whether disabling the sandbox solves the issue for you by setting security.sandbox.content.level to 0.

Trac:
Cc: N/A to jllover
Priority: Medium to High
Severity: Normal to Major

Trac:
Cc: jllover to jllover, arthuredelstein

Trac:
Status: new to assigned
Owner: tbb-team to pospeselr

Trac:
Cc: jllover, arthuredelstein to jllover, arthuredelstein, mcs

Was able to reproduce on a Vista 64-bit SP2 VM this afternoon and also confirmed the issue does not occur on 32-bit. Setting sandbox content level to 0 'fixes' the issue.

Trac:
Keywords: N/A deleted, TorBrowserTeam201802 added

Vista is vulnerable without security patches. Why are you wasting your resources on it?

Trac:
Status: assigned to needs_information

Replying to cypherpunks:

Vista is vulnerable without security patches. Why are you wasting your resources on it? But the current ESR of Firefox still supports Vista and XP, which means that TB should support them as well as ditch them when Firefox ditches them (i.e. this next ESR).

Trac:
Status: needs_information to assigned

This failure happens due to a missing wow_helper.exe in the TBB package. Everything works just fine when I copy over the version packaged with latest Firefox. Currently investigating why this exe isn't being built or packaged.

An interesting sidenote, the latest Chromium sandbox code no longer uses wow_helper.exe. Seems like it was removed in Chromium commit 1812d0d777dbe2162e88f6a0a205c8b483008626 as part of removing support for XP and Vista.

Replying to pospeselr:

This failure happens due to a missing wow_helper.exe in the TBB package. They didn't tell you? Everything works just fine when I copy over the version packaged with latest Firefox. What do you mean? It was removed as part of removing support for Vista. Currently investigating why this exe isn't being built or packaged. The same way why helper.exe isn't being built, and then they wonder why staged updates don't work. An interesting sidenote, the latest Chromium sandbox code no longer uses wow_helper.exe. Seems like it was removed in Chromium commit 1812d0d777dbe2162e88f6a0a205c8b483008626 as part of removing support for XP and Vista. It was needed for Vista only.

Trac:
Status: assigned to needs_information

So, FWIW, we are hitting essentially https://bugzilla.mozilla.org/show_bug.cgi?id=1110760.

Trac:
Status: needs_information to assigned

Trac:
Cc: jllover, arthuredelstein, mcs to jllover, arthuredelstein, mcs, tbb-team

Trac:
Keywords: TorBrowserTeam201802 deleted, TorBrowserTeam201802R added

Trac:
Status: assigned to needs_review
Keywords: TorBrowserTeam201802R deleted, TorBrowserTeam201803R added

I don't have a way to test this patch, but it looks okay. I have a few comments:

• To match Mozilla's style inside GeckoChildProcessHost.cpp you should add a space after the if keywords.
• It is okay to check for the existence of IsWow64Process() but I think it will be present in all versions of Windows we care about since I am pretty sure we required WinXP sp2 or later. That said, I am not sure what happens if you try try to run on something older so maybe we should keep the GetProcAddress fun.
• I don't think having TweakSandboxLevel() adds much; I would just put code like this inside GeckoChildProcessHost::PrepareLaunch():

  if (ShouldLowerSandboxLevel(mSandboxLevel)) {
    mSandboxLevel = 0;
  }

I tested on a Windows 7 and Windows 8 box both 64bit and 32bit Tor Browser builds and they behaved as they should. Marking this as needs_revision for the things mcs and brade found.

Trac:
Keywords: TorBrowserTeam201803R deleted, TorBrowserTeam201803 added
Status: needs_review to needs_revision