1594404 - Crash in [@ mozilla::AutoSafeJSContext::AutoSafeJSContext]

Status: RESOLVED FIXED

(Core :: XPConnect, defect)

Description

[Pascal Chevrel:pascalc (PTO until April 26)]

This bug is for crash report bp-3fcbd07a-642b-40b0-8c8d-b71d00191106.

Top 10 frames of crashing thread:

0 xul.dll mozilla::AutoSafeJSContext::AutoSafeJSContext dom/script/ScriptSettings.cpp:716
1 xul.dll static nsresult CentralizedAdminPrefManagerInit extensions/pref/autoconfig/src/nsJSConfigTriggers.cpp:54
2 xul.dll nsresult nsReadConfig::readConfigFile extensions/pref/autoconfig/src/nsReadConfig.cpp:163
3 xul.dll nsresult nsReadConfig::Observe extensions/pref/autoconfig/src/nsReadConfig.cpp:91
4 xul.dll nsObserverList::NotifyObservers xpcom/ds/nsObserverList.cpp:66
5 xul.dll nsObserverService::NotifyObservers xpcom/ds/nsObserverService.cpp:291
6 xul.dll mozilla::Preferences::InitializeUserPrefs modules/libpref/Preferences.cpp:3672
7 xul.dll nsXREDirProvider::InitializeUserPrefs toolkit/xre/nsXREDirProvider.cpp:886
8 xul.dll nsresult XREMain::XRE_mainRun toolkit/xre/nsAppRunner.cpp:4401
9 xul.dll int XREMain::XRE_main toolkit/xre/nsAppRunner.cpp:4740

Comment 1

[Julien Cristau [:jcristau]]

Started showing up in the 20191106095742 nightly build.

Comment 2

[Julien Cristau [:jcristau]]

Mike, FYI, this seems to involve autoconfig somehow.

Comment 3

[Ryan VanderMeulen [:RyanVM]]

Regression range:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=4d585c7edc76&tochange=d73cfe3a04e90b5dff64f6d4e3c3a9183aec4ec5

Bug 1579367 maybe?

Comment 4

[Jan de Mooij [:jandem]]

OK apparently we have no tests for this autoconfig thing? :/

Comment 5

[Jan de Mooij [:jandem]]

I can 'fix' this by loading autoconfig after we initialize JS. That means autoconfig files can't set or affect JS engine startup prefs because that's a chicken-and-egg problem. That was also the situation before bug 1579367 so it's not making anything worse.

Comment 6

[Mike Kaply [:mkaply]]

We do have tests for Autoconfig:

https://searchfox.org/mozilla-central/source/extensions/pref/autoconfig/test/unit

But they are xpcshell

We couldn't figure out how to test things that require files laid down before Firefox even starts.

Comment 7

[Jan de Mooij [:jandem]]

Attachment: Bug 1594404 - Notify preference loading observers after initializing JS. r?kmag!

This fixes crashes when using autoconfig files.

Comment 8

[Jan de Mooij [:jandem]]

The patch I posted seems to fix this locally. It's not pretty but I think it's the best we can do given autoconfig requires JS execution.

Comment 9

[Pascal Chevrel:pascalc (PTO until April 26)]

1000 startup crashes in the last 4 hours, I stopped nightly updates and will ask sheriffs to backout bug 1579367 and respin nightlies.

Comment 10

[Kris Maglione [:kmag]]

(In reply to Mike Kaply [:mkaply] from comment #6)

We do have tests for Autoconfig:

https://searchfox.org/mozilla-central/source/extensions/pref/autoconfig/test/unit

But they are xpcshell

We couldn't figure out how to test things that require files laid down before Firefox even starts.

You should be able to do that with Marionette.

Comment 11

[Mike Kaply [:mkaply]]

I'm shocked that all these folks have autoconfig on nightly. Is autoconfig always in the call stack?

Comment 12

[Andrew McCreight [:mccr8]]

(In reply to Mike Kaply [:mkaply] from comment #11)

I'm shocked that all these folks have autoconfig on nightly. Is autoconfig always in the call stack?

There's around 1300 of these crashes on the latest Nightly build, from 170 installations. Splitting them up by proto-signature, at least 1200 of them look roughly like those in comment 0.

Comment 13

[Kris Maglione [:kmag]]

(In reply to Mike Kaply [:mkaply] from comment #11)

I'm shocked that all these folks have autoconfig on nightly. Is autoconfig always in the call stack?

It appears to be. Unfortunately, I suspect a lot of people still use autoconfig as a hack to execute chrome JS.

Comment 14

[Steven Noonan]

(In reply to Kris Maglione [:kmag] from comment #13)

(In reply to Mike Kaply [:mkaply] from comment #11)

I'm shocked that all these folks have autoconfig on nightly. Is autoconfig always in the call stack?

It appears to be. Unfortunately, I suspect a lot of people still use autoconfig as a hack to execute chrome JS.

I use it to load a mozilla.cfg file (via general.config.filename), which applies a bunch of lockPref/defaultPref/pref stuff that I want to have on every one of my Firefox installs. If there's documentation about how to do this any other way, it's very hard to find.

Comment 15

[Mike Kaply [:mkaply]]

(In reply to Steven Noonan from comment #14)

I use it to load a mozilla.cfg file (via general.config.filename), which applies a bunch of lockPref/defaultPref/pref stuff that I want to have on every one of my Firefox installs. If there's documentation about how to do this any other way, it's very hard to find.

That's a correct use for it.

You should be able to do that with Marionette.

https://bugzilla.mozilla.org/show_bug.cgi?id=1594584

Comment 17

[Jan de Mooij [:jandem]]

Fixed by backout. I'll try landing bug 1579367 again in a few days and fold the patch here into it...

Comment 18

[Pascal Chevrel:pascalc (PTO until April 26)]

(In reply to Pascal Chevrel:pascalc from comment #9)

1000 startup crashes in the last 4 hours, I stopped nightly updates and will ask sheriffs to backout bug 1579367 and respin nightlies.

Nightly updates are restored.

Comment 19

[Firefox Bug Husbandry Bot]

Please specify a root cause for this bug. See :tmaity for more information.

Comment 20

[Andrew Overholt [:overholt]]

(In reply to Firefox Bug Husbandry Bot from comment #19)

Please specify a root cause for this bug. See :tmaity for more information.

Jan, could you take a look at the root cause here?

Comment 21

[Jan de Mooij [:jandem]]

I'll go with Testing Error because we were missing tests (since fixed) that would have caught this.