Tor browser is crashing on exit on Windows

[WalrusInAnus]

Ever since I updated to the latest version 7, the browser crashes every single time on exit.
I have no idea if there are any hidden logs anywhere, but this is what I can see in Windows EventLog:
Faulting application name: firefox.exe, version: 52.1.2.6242, time stamp: 0x00000000
Faulting module name: nssckbi.dll_unloaded, version: 0.0.0.0, time stamp: 0x00000000
Exception code: 0xc0000005
Fault offset: 0x624cda4c
Faulting process id: 0x1344
Faulting application start time: 0x01d2e38545d0b59e
Faulting application path: F:\Programy\Tor Browser\Browser\firefox.exe
Faulting module path: nssckbi.dll
Report Id: bf91d4dc-4f78-11e7-bfb4-902b34ddceaf

[gk]

Does the browser crash as well if you are not surfing to some website but are rather just opening it and then closing it again? Which Windows version is that?

[WalrusInAnus]

I am on Windows 7 x64.
It doesn't matter if I close the browser right after starting it or after an hour. I always get the crash message right after the window disappears.

Now that I think about it, I get crashes after running for longer periods of time too, but I don't do that very often so I am not sure if it's the same type of crash (the dll in question).

[cypherpunks]

Measure the time from pressing Exit and a crash, if it is more than 60 sec - it's a "feature"!

[WalrusInAnus]

No, it's like half a second to a second.

[cypherpunks]

dll_unloaded is suspicious. Do you have some "security" programs installed?

[WalrusInAnus]

Yes. I use Eset Smart Security.

[cypherpunks]

Remove it and test again.

[WalrusInAnus]

That's complete nonsense.
Are you even a part of the TOR devteam? I don't want to waste time talking to someone who has no idea.

[cypherpunks]

Nonsense is your "Eset Smart Security". Tor team is busy with Tor, and this is a Tor Browser, and its team is busy too.

[gk]

Calm down folks. WalrusInAnus could you remove that tool (disabling might not be enough) and test again? This is actually no nonsense. We have seen in the past a lot of "security" tools that are intercepting/interfering (with) the browser or tor and are causing crashes. This might be another instance of that.

[WalrusInAnus]

Well I've been using it for several years now AND I didn't have the crashing problem with TOR version 6 (any of them I believe), so it definitely is not the cause. It started again when TOR updated to v7.

[WalrusInAnus]

I've tried it on different PC with no antivirus software installed though, and with same result.

[cypherpunks]

Then it's a virus))

[WalrusInAnus]

Please stop commenting.

[gk]

Replying to WalrusInAnus:

Well I've been using it for several years now AND I didn't have the crashing problem with TOR version 6 (any of them I believe), so it definitely is not the cause. It started again when TOR updated to v7.

Alright, I just looked at it on my Windows 7 64bit machine but could not reproduce these problems. Do they go away if you set browser.tabs.remote.autostart.2 to false in your about:config and restart Tor Browser (this disables the multiprocess mode, maybe the crash is related to that one on your computer)?

[WalrusInAnus]

Nope, unfortunately no change.
I tried a fresh "installation" as well in case it was something wrong with the profile (which I've been using for quite some time), but no luck.
Are there old TOR versions to be downloaded from somewhere? I'd like to confirm v6 doesn't crash like I believe it didn't.

[gk]

​https://archive.torproject.org/tor-package-archive/torbrowser/

[WalrusInAnus]

Ok. Version 6.5a6 does not crash. Version 7 does (and so did the alphas or whatever the unstable versions are called).

[gk]

Could you test 6.5.2 which is the last stable before the switch to 7.0? Would you be willing to run test builds if I'd give some to you to track the problem down? Oh, another question: Does a normal Firefox 52 ESR crash for you as well (​https://www.mozilla.org/en-US/firefox/organizations/all/)?

[WalrusInAnus]

Oh I thought I grabbed the last version before 7. Let me try again.
I'll go with completely clean installation too. Brb.

[WalrusInAnus]

Well, uh. I downloaded v7 again, installed to completely new folder with a new profile, and thus far it seems it's not crashing.
Are you interested in a log from my regular installation to maybe try to figure out what went wrong? Something might have broken during upgrade from v6 to v7 (which could happen to others I guess).

edit: Firefox works just fine.

[gk]

Replying to WalrusInAnus:

Well, uh. I downloaded v7 again, installed to completely new folder with a new profile, and thus far it seems it's not crashing.
Are you interested in a log from my regular installation to maybe try to figure out what went wrong? Something might have broken during upgrade from v6 to v7 (which could happen to others I guess).

What do you mean with "log"? What would help would be a diff between both folders trying to narrow down the difference that is causing the problem. Could you help with that?

[WalrusInAnus]

Well, Tor has logging built in, which is enabled from within torrc file. I thought it might be of some use.
Don't know how to do the diff thing though, unfortunately. Which folders should I compare and how?

[cypherpunks]

No matter

[gk]

Replying to WalrusInAnus:

Well, Tor has logging built in, which is enabled from within torrc file. I thought it might be of some use.

Hm, maybe although I currently doubt that as it is the browser which is crashing. So, let's take this road later in case we have not solved the issue and have no clue on how to make progress.

Don't know how to do the diff thing though, unfortunately. Which folders should I compare and how?

Not sure how to do that efficiently on Windows but you could do the following things:

1) Copy the broken setup to a new folder (only use the one in the new folder for debugging; in case anything goes wrong you still have the broken setup at the original location to start over)
2) Test that it is still broken in the new folder
3) If 2) is the case remove the TorBrowser directory and everything below it (it is located in the Browser folder) and replace it with the TorBrowser contents of the working setup
4) Test whether it is still broken

This should help us narrow the issue down a lot and we can think about how to proceed further depending on the results.

[WalrusInAnus]

Replacing the TorBrowser folder stopped the crashing.

[gk]

Thanks, then you could start with 1) again but this time replace the Data directory in Browser\TorBrowser and see whether the problem is in that one.

[WalrusInAnus]

Still no crashes. We're getting somewhere.

[gk]

Okay, the crashes are caused by something in your Data directory then. Let's see. Do the crashes stop if you replace Browser\TorBrowser\Data\Browser? If som please test with replacing Browser\TorBrowser\Data\Tor as well to double-check that we did not make any mistakes. Exactly one of them should still lead to crashes.

[WalrusInAnus]

Replacing \Browser\TorBrowser\Data\Tor\ had no effect, but \Browser\TorBrowser\Data\Browser\ stopped the crashes.

That could indicate something rotten in the user profile, BUT if I do a clean install and copy the existing profile in there, it's not crashing.

[cypherpunks]

Can you find nssckbi.dll_unloaded somewhere in the broken browser's folders?

[gk]

Replying to WalrusInAnus:

Replacing \Browser\TorBrowser\Data\Tor\ had no effect, but \Browser\TorBrowser\Data\Browser\ stopped the crashes.

That could indicate something rotten in the user profile, BUT if I do a clean install and copy the existing profile in there, it's not crashing.

Weird. But we still have a way forward to narrow things down. I don't know how your profile directory looks like but I guess you know how to narrow the issue down further? Could you get back to us if you have found the culprit? And the question regarding nssckbi.dll_unloaded is a good one as well.

[WalrusInAnus]

There's no such file anywhere. Only nssckbi.dll in \Browser\
I'll keep trying to randomly replace files and see if I come up with something.

[WalrusInAnus]

It seems like it could be something in prefs.js (when I deleted and let it regenerate, the crashing stopped), but that's as far as I'm able to troubleshoot it. I don't know anything about the inner workings of Firefox.

[cypherpunks]

Attach it here, let's take a look.

[WalrusInAnus]

Allright, done.

[cypherpunks]

Just don't use TorBrowser for Windows. Firefox for Windows were never used for real after to be built with MinGW.
PS: or use it only with default settings (private browsing mode must be enabled for TorBrowser, etc)

[gk]

Replying to WalrusInAnus:

Allright, done.

Thanks. So, looking at your preferences file and on our previous issues it seems you might have been running into something we had fixed in #13610/#10761. Could you go to about:preferences#privacy in your broken Tor Browser and make sure to select the "Never remember history" option and do a restart. Do the crashes still occur afterwards?

[WalrusInAnus]

I thought we were finished (in part due to the other guy's nonsense comments here) and have since deleted the old profile and started anew. Sorry.

[gk]

Replying to WalrusInAnus:

I thought we were finished (in part due to the other guy's nonsense comments here) and have since deleted the old profile and started anew. Sorry.

No worries. If similar things come up again we'll know where to look I guess. :)

[cypherpunks]

worksforme

Then you need to disable changing for about:preferences#privacy or something yet, who knows what config can to brick user's privacy/expirience again if browser unsupport mingw build env for real.

[gk]

Replying to cypherpunks:

worksforme

Then you need to disable changing for about:preferences#privacy or something yet, who knows what config can to brick user's privacy/expirience again if browser unsupport mingw build env for real.

It's not clear whether my theory in comment:39 is actually true. I could not reproduce the problem following the steps in #10761.

[cypherpunks]

I could not reproduce the problem following the steps in #10761.

Because it's race condition, in ideal world (where users with bug lives) dll unloaded just after last FreeLibrary() called, in non-ideal world (where users without bug lives) code with thunk from freed library still in place and PR_Free() successfully finished.

[gk]

I am wondering, though, why this is happening again (assuming it is really something like #10761) because it seemed to me the underlying issues got fixed and the fixes are available in esr45/esr52.

[cypherpunks]

​https://hg.mozilla.org/mozilla-central/rev/169d5dfe505f

[gk]

Replying to cypherpunks:

​https://hg.mozilla.org/mozilla-central/rev/169d5dfe505f

What do you mean to say with that changelog? That the usage of -mnop-fun-dllimport is back and the reason for the crashes (even though it got fixed in upstream NSS with ​https://bugzilla.mozilla.org/show_bug.cgi?id=1151447)?

[cypherpunks]

​https://gitweb.torproject.org/tor-browser.git/tree/config/external/nss/Makefile.in?h=tor-browser-52.2.0esr-7.0-1#n273

[gk]

I have found a machine where I can reproduce this issue. Putting this ticket on my radar then.

[gk]

Moving my tickets to the new month.

[gk]

Items for September 2017.

[cypherpunks]

FWIW: this is ​https://bugzilla.mozilla.org/show_bug.cgi?id=1389967

[sudha@…]

I have seen this bug since ages ago, most likely from the first 7a version. Certainly it is present on all 7 alphas for windows.

Steps to reproduce from fresh install are very easy -- I have reproduced that on three different systems, Win8.1, Win10 1703 and 1607 builds.

What's worse, after quite a while of such usage the Tor profile can appear very corrupted -- to the point that tor browser starts crashing on start, or more specifically -- start browser and then click on a tab get a crash.

[gk]

Items for October 2017

[gk]

Moving my tickets to November.

[gk]

FWIW here is the stack trace I get when crashing:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 1048.0x1cc]
0x6edfda4c in ?? ()
(gdb) bt
#0  0x6edfda4c in ?? ()
#1  0x634cca60 in _PR_DestroyThreadPrivate ()
   from C:\Users\user\Desktop\Tor Browser\Browser\nss3.dll
#2  0x634cbb1a in _PR_CleanupThread ()
   from C:\Users\user\Desktop\Tor Browser\Browser\nss3.dll
#3  0x634ca36c in _PR_NativeRunThread ()
   from C:\Users\user\Desktop\Tor Browser\Browser\nss3.dll
#4  0x634bc19e in pr_root@4 ()
   from C:\Users\user\Desktop\Tor Browser\Browser\nss3.dll
#5  0x6c29c556 in endthreadex ()
   from C:\Users\user\Desktop\Tor Browser\Browser\msvcr100.dll
#6  0x6c29c600 in endthreadex ()
   from C:\Users\user\Desktop\Tor Browser\Browser\msvcr100.dll
#7  0x7572ef8c in KERNEL32!AcquireSRWLockExclusive ()
   from C:\Windows\system32\kernel32.dll
#8  0x76ed367a in ntdll!RtlInsertElementGenericTableAvl ()
   from C:\Windows\system32\ntdll.dll
#9  0x76ed364d in ntdll!RtlInsertElementGenericTableAvl ()
   from C:\Windows\system32\ntdll.dll
#10 0x00000000 in ?? ()

[gk]

Moving tickets over to November.

[gk]

Moving tickets to December 2017

[gk]

Moving tickets to December 2017, for realz.

[gk]

Moving my tickets to December.

[gk]

Moving my tickets to 2018

[gk]

Moving tickets to 2018.

[gk]

Moving my tickets to Feb.

[gk]

Moving tickets to Feb

[gk]

Moving my tickets to March.

[gk]

Adding to our March plate.

[gk]

Should be fixed in the upcoming alpha (8.0a9) with the backport of the fix for bug 1389967.