Auth crashes from main and worker threads accessing a Set of AuthKeychainServices

[importRyan]

Description

We're seeing a few crash paths from concurrent access of a Set private to AuthKeychainServices in the 11.12.0 SDK (and going back several versions). I believe it is this one.

Below are a few traces of variants of that crash, some on com.google.firebase.auth.globalWorkQueue and some on main. All of these crashes occur early, while didFinishLaunchingWithOptions is in scope. There we call Firebase.configure()and then Auth.getStoredUser(forAccessGroup: nil) as part of a local-to-iCloud keychain migration routine.

Traces
onGlobal-1.txt
onGlobal-2.txt
main-1.txt
main-2.txt

Reproducing the issue

No response

Firebase SDK Version

11.12.0

Xcode Version

16.3

Installation Method

Swift Package Manager

Firebase Product(s)

Authentication, Crashlytics, All

Targeted Platforms

iOS

Relevant Log Output

If using Swift Package Manager, the project's Package.resolved

Expand Package.resolved snippet

{
  "originHash" : "36fae030e83cb8526a95be9834168f8c82b08dfcc2148980f2c8c81fd2ed565a",
  "pins" : [
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      "identity" : "abseil-cpp-binary",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/abseil-cpp-binary.git",
      "state" : {
        "revision" : "bbe8b69694d7873315fd3a4ad41efe043e1c07c5",
        "version" : "1.2024072200.0"
      }
    },
    {
      "identity" : "app-check",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/app-check.git",
      "state" : {
        "revision" : "61b85103a1aeed8218f17c794687781505fbbef5",
        "version" : "11.2.0"
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      "kind" : "remoteSourceControl",
      "location" : "https://github.com/firebase/firebase-ios-sdk",
      "state" : {
        "revision" : "fbd463894af94d90eb4d6a4e54080459a8179519",
        "version" : "11.12.0"
      }
    },
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      "identity" : "googleappmeasurement",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/GoogleAppMeasurement.git",
      "state" : {
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        "version" : "11.12.0"
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      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/GoogleDataTransport.git",
      "state" : {
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        "version" : "10.1.0"
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    },
    {
      "identity" : "googleutilities",
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      "location" : "https://github.com/google/GoogleUtilities.git",
      "state" : {
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        "version" : "8.0.2"
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    },
    {
      "identity" : "grpc-binary",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/grpc-binary.git",
      "state" : {
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      "kind" : "remoteSourceControl",
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      "state" : {
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        "version" : "3.5.0"
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    {
      "identity" : "interop-ios-for-google-sdks",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/interop-ios-for-google-sdks.git",
      "state" : {
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        "version" : "101.0.0"
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    },
    {
      "identity" : "leveldb",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/firebase/leveldb.git",
      "state" : {
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        "version" : "1.22.5"
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      "location" : "https://github.com/firebase/nanopb.git",
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    {
      "identity" : "swift-protobuf",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/apple/swift-protobuf.git",
      "state" : {
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  ],
  "version" : 3
}

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[ncooke3]

Thanks, @importRyan, for the report and apologies for the trouble. I merged a fix in #14862 to make that class thread-safe. It will release in 11.14 (est. release is week of June 3).

[importRyan]

Brilliant! Thanks for that.