Firestore: Make ListenerRegistration::Remove() thread-safe #10065
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dconeybe
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master
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dconeybe/RemoveFirestoreAbslCheck
Coverage Report 1Affected Products
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ehsannas
approved these changes
Aug 4, 2022
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This fixes a latent bug in Firestore's
ListenerRegistration::Remove()where it could use invalid memory if invoked concurrently. The fix is to simply guard the entire method's body with a mutex.The issue is that one thread could use
client_(ashared_ptr) that has been reset by another thread. Specifically, in this code blockfirebase-ios-sdk/Firestore/core/src/api/query_listener_registration.cc
Lines 47 to 53 in 26075af
one thread could invoke
client_.reset()on line 53 just before another thread invokesclient_->RemoveListener(query_listener)on line 49.This may be the root cause of #10026 and #9302. I'll ask the customer to report back once they upgrade to a version that contains this fix.