Fix TOCTOU race in gossip discovery handleAliveMessage#5397
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Ady0333 wants to merge 1 commit intohyperledger:mainfrom
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Fix TOCTOU race in gossip discovery handleAliveMessage#5397Ady0333 wants to merge 1 commit intohyperledger:mainfrom
Ady0333 wants to merge 1 commit intohyperledger:mainfrom
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Consolidate three separate RLock/RUnlock pairs into a single atomic
read to prevent concurrent purge() from removing a member between
checks, which caused a panic ("not found in alive nor dead") or nil
pointer dereference in learnExistingMembers.
Signed-off-by: Ady0333 <adityashinde1525@gmail.com>
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Hi @yacovm, when you get a chance, could you please review this PR? |
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Type of change
Description
This PR fixes a TOCTOU race in gossip discovery that could crash a peer during normal operation.
handleAliveMessage()previously read membership state using multiple separateRLock/RUnlocksections and then treated the combined result as consistent. If a concurrentpurge()ran between these lock gaps (for example during identity changes or message expiration), a member could appear as “known” but neither alive nor dead, triggering aPanicf. In another path, the same race could lead to a nil pointer dereference inlearnExistingMembers().The fix consolidates all membership state reads into a single atomic
RLocksection and adds a defensive nil guard when updating existing members. This ensures inconsistent intermediate states are never observable and avoids crashing the peer.Additional details
The change is localized to gossip discovery logic and does not affect normal behavior.
Tested locally with
go test ./gossip/....Release Note
Fixes a gossip discovery race where concurrent member purging could cause
a peer panic during normal operation.