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bls: Guard null contribution verification vector #1926

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bls: Guard null contribution verification vector #1926

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6 changes: 5 additions & 1 deletion src/bls/bls_worker.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -755,7 +755,11 @@ std::future<bool> CBLSWorker::AsyncVerifyContributionShare(const CBLSId& forId,
const BLSVerificationVectorPtr& vvec,
const CBLSSecretKey& skContribution)
{
if (!forId.IsValid() || !VerifyVerificationVector(*vvec)) {
// vvec may be null when the verification vector for that member was never
// received (e.g. a non-member observer that did not get the member's QCONTRIB).
// Dereferencing it here is a remote-triggerable crash; treat a missing vvec as a
// failed verification, mirroring the null check in VerifyVerificationVectors().
if (!forId.IsValid() || vvec == nullptr || !VerifyVerificationVector(*vvec)) {

@codeant-ai codeant-ai Bot Aug 29, 2026

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Suggestion: The full VerifyVerificationVector scan now runs synchronously before the job is submitted, so this method is no longer asynchronous for valid inputs. CDKGSession::VerifyJustification invokes it once per contribution while processing a received justification, causing the same verification vector to be revalidated repeatedly on the message-processing thread and allowing a large vector to block that thread. Keep the null/ID guard synchronous, but perform vector validation inside the worker task or rely on the validation already performed when the contribution was received. [performance]

Severity Level: Major ⚠️ 
- ⚠️ DKG justification handling rescans vectors synchronously.
- ⚠️ Multiple contributions multiply message-thread validation cost.
- ⚠️ Large vectors can delay subsequent DKG messages.

Use CodeAnt Skill Fix in Cursor Fix in VSCode Claude

Prompt for AI Agent 🤖 
This is a comment left during a code review.

**Path:** src/bls/bls_worker.cpp
**Line:** 762:762
**Comment:**
	*Performance: The full `VerifyVerificationVector` scan now runs synchronously before the job is submitted, so this method is no longer asynchronous for valid inputs. `CDKGSession::VerifyJustification` invokes it once per contribution while processing a received justification, causing the same verification vector to be revalidated repeatedly on the message-processing thread and allowing a large vector to block that thread. Keep the null/ID guard synchronous, but perform vector validation inside the worker task or rely on the validation already performed when the contribution was received.

Validate the correctness of the flagged issue. If correct, How can I resolve this? If you propose a fix, implement it and please make it concise.
Once fix is implemented, also check other comments on the same PR, and ask user if the user wants to fix the rest of the comments as well. if said yes, then fetch all the comments validate the correctness and implement a minimal fix
👍 | 👎

auto p = BuildFutureDoneCallback<bool>();
p.first(false);
return std::move(p.second);
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20 changes: 20 additions & 0 deletions src/test/bls_tests.cpp
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Expand Up @@ -4,6 +4,7 @@

#include "bls/bls.h"
#include "bls/bls_batchverifier.h"
#include "bls/bls_worker.h"
#include "test/test_bitcoin.h"

#include <boost/test/unit_test.hpp>
Expand Down Expand Up @@ -154,4 +155,23 @@ BOOST_AUTO_TEST_CASE(batch_verifier_tests)
Verify(msgs);
}

BOOST_AUTO_TEST_CASE(bls_verify_contribution_share_null_vvec_tests)
{
CBLSWorker worker;
worker.Start();

const CBLSId id{uint256S("1")};
BOOST_REQUIRE(id.IsValid());

CBLSSecretKey sk;
sk.MakeNewKey();

const BLSVerificationVectorPtr nullVvec;
BOOST_REQUIRE(nullVvec == nullptr);

BOOST_CHECK(worker.AsyncVerifyContributionShare(id, nullVvec, sk).get() == false);

worker.Stop();
}

BOOST_AUTO_TEST_SUITE_END()
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