1977347 - Microsoft SSO authentication hanging on 140.0x (Mac)

Status: RESOLVED FIXED

(Core :: Security: PSM, defect, P1)

Description

[Phil Evans]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:140.0) Gecko/20100101 Firefox/140.0

Steps to reproduce:

In Firefox 140.0.4 (aarch64) on my Macbook Pro (MacOS 15.5), I visited a work webpage (not public) that runs "SAP" -- this authenticates users against Microsoft AD, via https://login.microsoftonline.com and should redirect me to the SSO login page.

Actual results:

Firefox does literally nothing. The page doesn't load, and the "loading" icon on the tab runs continuously. Also, any other open tabs lose internet connectivity. If I quit Firefox, the window closes but the application doesn't -- it becomes unresponsive and has to be force quit.

If I open the "Web developer tools", and enable everything in the "Console" tab, all it shows is the GET request to the URL, with no response -- as does the "Network" tab. However, Wireshark tells me that there was an exchange of information between my computer and the web server's IP (on port 443), including "Server Key Exchange, Certificate Request, Server Hello Done", shortly followed by traffic to and from one of the Microsoft identity servers (www.tm.a.prd.aadg.akadns.net). None of this is showing in the firefox console.

I am running on an Apple M3 Macbook Pro, MacOS 15.5. I have tried using a fresh Firefox profile, and tried this on a different Mac (in Intel-based Macbook Pro, also MacOS 15.5) and asked a colleague to try on their Mac. In all cases the same problem occurs. Chrome and Safari work fine, and even running "curl" on the URL works (in that it returns a page, which is just a redirect to login.microsoft.com, but nonetheless is confirms receipt of data).

I have tried various regressions -- the behaviour above occurs on all Firefox versions 140.x Whereas on Firefox 139.0.4, and Firefox ESR 128.12.0 the page loads correctly.

I infer, therefore, that this is related to a change introduced in Firefox 140.0

Expected results:

I should have been redirected to https://login.microsoftonline.com and given the single sign-in authentication page for my institute. The Firefox console should also have logged the response to the GET query and shown evidence of traffic. Other tabs should not have lost their internet connectivity, and on quit, Firefox should quite instead of hanging.

Comment 1

[BugBot [:suhaib / :marco]]

The Bugbug bot thinks this bug should belong to the 'Core::Widget: Cocoa' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Stephen A Pohl [:spohl]]

Could you run mozregression to see when exactly this started happening? You can either choose to use the GUI tool, or simply run these three commands in a Terminal window:

sudo easy_install pip
sudo python3 -m pip install -U mozregression --ignore-installed
mozregression --good 2017-01-01

A number of Firefox versions will open in succession to narrow down when this started occurring. Simply type "good" or "bad" in Terminal based on whether or not a build reproduces the bug. Once finished, please post the output from the last run. It should give a last good and first bad revision as well as a link to look at the changesets in that range. Thank you!

Comment 3

[Phil Evans]

(In reply to Stephen A Pohl [:spohl] from comment #2)

Here's the output:

15:03.34 INFO: Narrowed integration regression window from [f47850a3, 9b0a9ebb] (3 builds) to [f47850a3, af5cca52] (2 builds) (~1 steps left)
15:03.34 INFO: No more integration revisions, bisection finished.
15:03.34 INFO: Last good revision: f47850a3514e1f722f01ce225cea1f51dc2daed9
15:03.34 INFO: First bad revision: af5cca52d3c61a9a27a9aa36356209862c17ea3e
15:03.34 INFO: Pushlog:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=f47850a3514e1f722f01ce225cea1f51dc2daed9&tochange=af5cca52d3c61a9a27a9aa36356209862c17ea3e

I had a look at the changeset in the range as well out of curiosity and the description of it (related to Bug 1962280, calls to the OS APIs to access certificates) sounds like it could easily have inadvertently caused this issue. I declined to learn your codebase and look up the various APIs and so as to try to debug it myself ;)

Comment 4

[BugBot [:suhaib / :marco]]

:keeler, since you are the author of the regressor, bug 1962280, could you take a look?

For more information, please visit BugBot documentation.

Comment 5

[Dana Keeler (she/her) [:keeler]]

Can you enable the profiler (https://profiler.firefox.com/) and capture a profile with the custom threads set to "socket,ssl,osclientcerts"?

Comment 6

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1962280

Comment 7

[Phil Evans]

(In reply to Dana Keeler (she/her) [:keeler] from comment #5)

Can you enable the profiler (https://profiler.firefox.com/) and capture a profile with the custom threads set to "socket,ssl,osclientcerts"?

This is not working for me -- I can enable the profiler and start it, open a new tab and paste in the "bad" URL, wait a few moments and press "capture", but at that point it tries to open a tab to https://profiler.firefox.com/from-browser.... ; but due to the impact of the bug, this tab doesn't load and after a few moments, Firefox stops responding.

If the profiler data are stored to a local file, I can dig that out and pass it on (actually, can I? I can't see an option on this page to attach a file).

I've tried find $profile_dir -mmin -1 -ls just after I stop the capture, and the only likely looking files are:

453073463       16 -rw-r--r--    1 pae9             _lpoperator          4152 15 Jul 21:07 ./storage/default/https+++profiler.firefox.com/cache/caches.sqlite-wal
453073448        8 -rw-r--r--    1 pae9             _lpoperator            69 15 Jul 21:07 ./storage/default/https+++profiler.firefox.com/.metadata-v2

Comment 8

[Dana Keeler (she/her) [:keeler]]

Can you use Sample Process with the macOS Activity Monitor? (select Firefox in the list of processes, click the "three dots in a circle" drop-down icon, and it should be an option there)

Comment 9

[Phil Evans]

Attachment: Sample output from ACtivity Monitor

Comment 10

[Phil Evans]

(In reply to Dana Keeler (she/her) [:keeler] from comment #8)

Can you use Sample Process with the macOS Activity Monitor? (select Firefox in the list of processes, click the "three dots in a circle" drop-down icon, and it should be an option there)

Done this and attached it (above); it didn't let me control when it stopped, so I hope it covers.
Also, here is the crash report generated just now as that version of FF crashed:

AdapterVendorID: 0x106b
AvailablePhysicalMemory: 472203264
AvailableSwapMemory: 0
BackgroundTaskMode: 0
BuildID: 20250707120347
Comments:  and a
ContentSandboxCapable: 1
ContentSandboxLevel: 3
CrashTime: 1752612761
DOMFissionEnabled: 1
DOMIPCEnabled: 1
EMCheckCompatibility: true
GpuSandboxLevel: 0
GraphicsNumActiveRenderers: 0
GraphicsNumRenderers: 0
HeadlessMode: 0
InstallTime: 1752087050
LastInteractionDuration: 59
LastStartupWasCrash: 0
MacAvailableMemorySysctl: 69
MacMemoryPressure: Normal
MacMemoryPressureCriticalTime: Unset
MacMemoryPressureNormalTime: 1752612635
MacMemoryPressureSysctl: 1
MacMemoryPressureWarningTime: Unset
MozCrashReason: Shutdown hanging at step AppShutdownNetTeardown. Something is blocking the main-thread.
NimbusEnrollments: upgrade-spotlight-rollout:treatment,encrypted-client-hello-fallback-mechanism:control,fx-accounts-ping-release-rollout-2:control,disable-ads-startup-cache:control,unified-api-for-spocs-and-top-sites-controlled-rollout-for-release-133:control,long-term-holdback-2025h1-growth-desktop:delivery,fox-doodle-multi-action-cta-2025-rollout:treatment-a,pdf-annotations-highlight-treatment-b-rollout:treatment-b,mozilla-vpn-in-private-browsing-treatment-d-rollout-en-only:treatment-d,tab-groups-50-rollout-no-onboarding:tab-groups,recommend-bookmark-toolbar-early-day-rollout:treatment-a,device-migration-accounts-toolbar-icon-rollout:treatment-a,desktop-address-autofill-uk-release-rollout:treatment-a,login-status-advisory-callout-rollout:treatment-a,chips-rollout-to-firefox:control,tab-groups-promotional-onboarding:onboarding,address-bar-update-rollout-v1:rollout,unified-search-button-callout-rollout-v1:control,account-adoption-callout-passwords-rollout:treatment-e,weather-rollout-united-kingdom:weather-suggestions-rollout,custom-wallpapers-no-message-rollout-release:control,spoc-positions-and-placements-rollout:control,storage-access-heuristic-restriction-rollout:treatment-branch,desktop-release-rollout-show-relay-to-all-browsers-next-sign-up-modal-cta:next-sign-up-modal-cta,simplified-chatbot-onboarding-short-copy-1-step-rollout:treatment-c-short-copy-1-step,1-callout-contextual-chatbot-suggestion-treatment-a-tab-switching-copy-rollout:treatment-a-tab-switching-copy,disable-enrollment-status-telemetry-for-firefox-desktop-via-nimbustelemetry:control,one-click-sponsored-settings:control,smart-tab-groups-rollout-worldwide-en-excluding-us:smart-tab-groups
Notes: FP(D10-L1000-W0000000-T01) WR? WR+ GL Context? GL Context+ 
ProductID: {ec8030f7-c20a-464f-9b0e-13a3a9e97384}
ProductName: Firefox
PurgeablePhysicalMemory: 1769848832
RDDProcessStatus: Running
ReleaseChannel: release
SafeMode: 0
SecondsSinceLastCrash: 3402
ShutdownProgress: profile-change-net-teardown
ShutdownReason: AppClose
StartupCacheValid: 1
StartupCrash: 0
StartupTime: 1752612635
SubmittedFrom: Client
TelemetryEnvironment: {"build":{"applicationId":"{ec8030f7-c20a-464f-9b0e-13a3a9e97384}","applicationName":"Firefox","architecture":"aarch64","buildId":"20250707120347","version":"140.0.4","vendor":"Mozilla","displayVersion":"140.0.4","platformVersion":"140.0.4","xpcomAbi":"aarch64-gcc3","updaterAvailable":true},"partner":{"distributionId":null,"distributionVersion":null,"partnerId":null,"distributor":null,"distributorChannel":null,"partnerNames":[]},"system":{"memoryMB":36864,"virtualMaxMB":null,"cpu":{"count":12,"cores":12,"pcount":6,"mcount":0,"ecount":6,"vendor":"","name":"Apple M3 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Throttleable: 1
TotalPhysicalMemory: 38654705664
URL: about:home
UptimeTS: 126.08333333333333
UtilityProcessStatus: Running
Vendor: Mozilla
Version: 140.0.4
XPCOMSpinEventLoopStack: default: nsHttpConnectionMgr::Shutdown
useragent_locale: en-GB
This report also contains technical information about the state of the application when it crashed.

Comment 11

[Dana Keeler (she/her) [:keeler]]

Thanks! To be clear, that's a sample from when you've visited the site and Firefox has frozen? Also, a crash report might be able to tell me something - can you link to one?

Comment 12

[Phil Evans]

(In reply to Dana Keeler (she/her) [:keeler] from comment #11)

Thanks! To be clear, that's a sample from when you've visited the site and Firefox has frozen? Also, a crash report might be able to tell me something - can you link to one?

Hi, Yes - I started the sample in Activity Monitor, and then immediately opened the URL in Firefox and it froze.

The crash report is pasted in the comment above (13:15 PDT), though I also accidentally allowed MacOS to submit the crash report as well at about the same time (in the UK, on BST, so rather out of sync with you for timezones I'm afraid!)

Phil

Comment 13

[Dana Keeler (she/her) [:keeler]]

Can you link the full crash report? (it should be listed in about:crashes)

Comment 14

[Phil Evans]

(In reply to Dana Keeler (she/her) [:keeler] from comment #13)

Can you link the full crash report? (it should be listed in about:crashes)

The crash ID listed is: d1e8267d-cdfc-4e2f-b2aa-b18850250715 -- is this enough for you to find it? It looks like the data are no longer stored locally.

Comment 15

[Dana Keeler (she/her) [:keeler]]

Great! I think I figured out what's going on. Basically, the implementation is trying to get a handle on your certificate/key, but it's failing, which is causing some resources to get released in a way the implementation isn't expecting, leading to a deadlock. The deadlock fix is straightforward, but I'm curious why getting the handles is failing - would you be able to email me a copy of the public part of your certificate? I'm assuming this is a decoding issue.

Comment 16

[Phil Evans]

(In reply to Dana Keeler (she/her) [:keeler] from comment #15)

• would you be able to email me a copy of the public part of your certificate? I'm assuming this is a decoding issue.

Done - you should have an email from me with the certificate attached.

Comment 17

[Dana Keeler (she/her) [:keeler]]

Attachment: Bug 1977347 - osclientcerts: check for already being on the right thread in ThreadSpecificHandles::drop r?jschanck

If a find_objects implementation encounters an error, it may release a
ThreadSpecificHandles on the background thread. Before this patch, this would
cause ThreadSpecificHandles::drop to block on the currently-running thread,
causing a deadlock. This patch changes the drop implementation to first check
if it's already on the background thread, in which case it can simply release
the resources without blocking on anything.

Comment 18

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1962280

Comment 19

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/71fe60e6251b
https://hg.mozilla.org/integration/autoland/rev/38b707f31ebe
osclientcerts: check for already being on the right thread in ThreadSpecificHandles::drop r=jschanck

Comment 20

[pstanciu]

https://hg.mozilla.org/mozilla-central/rev/38b707f31ebe

Comment 21

[BugBot [:suhaib / :marco]]

The patch landed in nightly and beta is affected.
:keeler, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
  • See https://wiki.mozilla.org/Release_Management/Requesting_an_Uplift for documentation on how to request an uplift.
• If no, please set status-firefox142 to wontfix.

For more information, please visit BugBot documentation.

Comment 22

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/ce83f4cf4484
https://hg.mozilla.org/mozilla-central/rev/c6c802b9d454
Revert "Bug 1977347 - osclientcerts: check for already being on the right thread in ThreadSpecificHandles::drop r=jschanck" for threading crashes

Comment 23

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

See these crashes:

• @ nsThread::Dispatch
• @ mozilla::ipc::MessagePumpForNonMainThreads::Run

Comment 24

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/41568f5b07ab
https://hg.mozilla.org/integration/autoland/rev/4bc88f9685cd
osclientcerts: check for already being on the right thread in ThreadSpecificHandles::drop r=jschanck

Comment 25

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/4bc88f9685cd

Comment 26

[Dana Keeler (she/her) [:keeler]]

Attachment: Bug 1977347 - osclientcerts: check for already being on the right thread in ThreadSpecificHandles::drop r?jschanck

If a find_objects implementation encounters an error, it may release a
ThreadSpecificHandles on the background thread. Before this patch, this would
cause ThreadSpecificHandles::drop to block on the currently-running thread,
causing a deadlock. This patch changes the drop implementation to first check
if it's already on the background thread, in which case it can simply release
the resources without blocking on anything.

Original Revision: https://phabricator.services.mozilla.com/D258085

Comment 27

[Phil Evans]

I've tested the latest nightly (2025-07-24-21-29-06) which is after the "first release with" in the above link (https://hg-edge.mozilla.org/mozilla-central/rev/4bc88f9685cd) and it is working perfectly now -- thank you :)

Comment 28

[Dana Keeler (she/her) [:keeler]]

Thank you!

Comment 29

[Phabricator Automation]

firefox-beta Uplift Approval Request

• User impact if declined: potential browser freezes
• Code covered by automated testing: no
• Fix verified in Nightly: yes
• Needs manual QE test: no
• Steps to reproduce for manual QE testing: n/a
• Risk associated with taking this patch: low
• Explanation of risk level: small change, has been validated by original reporter
• String changes made/needed: none
• Is Android affected?: no

Comment 30

[Dana Keeler (she/her) [:keeler]]

Attachment: Bug 1977347 - osclientcerts: check for already being on the right thread in ThreadSpecificHandles::drop r?jschanck

If a find_objects implementation encounters an error, it may release a
ThreadSpecificHandles on the background thread. Before this patch, this would
cause ThreadSpecificHandles::drop to block on the currently-running thread,
causing a deadlock. This patch changes the drop implementation to first check
if it's already on the background thread, in which case it can simply release
the resources without blocking on anything.

Original Revision: https://phabricator.services.mozilla.com/D258085

Comment 31

[Phabricator Automation]

firefox-esr140 Uplift Approval Request

• User impact if declined: potential hangs
• Code covered by automated testing: no
• Fix verified in Nightly: yes
• Needs manual QE test: no
• Steps to reproduce for manual QE testing: n/a
• Risk associated with taking this patch: low
• Explanation of risk level: small change, verified by original reporter
• String changes made/needed: none
• Is Android affected?: no

Comment 32

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/f5338fb5de1e
https://hg.mozilla.org/releases/mozilla-beta/rev/c746f9a972f1

Comment 33

[Dana Keeler (she/her) [:keeler]]

[Tracking Requested - why for this release]: potential hangs

Comment 34

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-esr140/rev/85e04e4c8bd5