fix: Copy mutable collections before passing to scope observers#7807
fix: Copy mutable collections before passing to scope observers#7807
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SentryScope passes mutable collections to scope observers inside @synchronized blocks. Observers like WatchdogTermination dispatch async work that iterates the collection after the lock is released, racing with concurrent mutations — causing EXC_BAD_ACCESS. Copy collections before passing to observers, consistent with the existing public getter methods that already return copies.
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Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #7807 +/- ##
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- Coverage 85.418% 85.130% -0.289%
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Files 487 487
Lines 29195 29207 +12
Branches 12632 12625 -7
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- Hits 24938 24864 -74
- Misses 4207 4292 +85
- Partials 50 51 +1
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antonis
requested review from
itaybre,
noahsmartin,
philipphofmann and
philprime
as code owners
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📜 Description
Copy mutable collections (
_contextDictionary,_tagDictionary,_extraDictionary,_fingerprintArray,_attributesDictionary) before passing them to scope observers inSentryScope.m. This prevents a race condition where observers dispatch async work that iterates the collection after the@synchronizedlock is released, while another thread mutates it concurrently.Also updates the misleading thread-safety comment in
SentryWatchdogTerminationScopeObserver.swiftto accurately describe the guarantee.💡 Motivation and Context
Fixes a launch crash (
EXC_BAD_ACCESSinobjc_msgSend) reported in getsentry/sentry-react-native#5995 affecting <1% of cold launches on iOS 26+. The crash occurs becauseSentryWatchdogTerminationScopeObservercaptures mutable collection references and dispatches async disk writes, racing with concurrent scope mutations.The public getter methods (
context,extras,tags,fingerprints,attributes) already return.copy— this fix makes observer notifications consistent with that pattern.💚 How did you test it?
testModifyingFromMultipleThreads_withObserverAsyncDispatch— a concurrent stress test that rapidly mutates scope context/tags/extras/fingerprint from multiple threads while an observer with async dispatch is activeSentryScopeSwiftTests(59 tests) passSentryWatchdogTerminationScopeObserverTests(18 tests) passmake format,make analyze,make build-iosall clean📝 Checklist
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