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Check against MANDATORY flags prior to accepting to mempool

Previously transactions were only tested again the
STANDARD_SCRIPT_VERIFY_FLAGS prior to mempool acceptance, so any bugs in
those flags that allowed actually-invalid transactions to pass would
result in allowing invalid transactions into the mempool. Fortunately
there is a second check in CreateNewBlock() that would prevent those
transactions from being mined, resulting in an invalid block, however
this could still be exploited as a DoS attack.
Peter Todd 6 years ago
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1 changed files with 15 additions and 0 deletions
  1. 15

+ 15
- 0
src/main.cpp View File

@@ -1039,6 +1039,21 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
return error("AcceptToMemoryPool: : ConnectInputs failed %s", hash.ToString());

// Check again against just the consensus-critical mandatory script
// verification flags, in case of bugs in the standard flags that cause
// transactions to pass as valid when they're actually invalid. For
// instance the STRICTENC flag was incorrectly allowing certain
// CHECKSIG NOT scripts to pass, even though they were invalid.
// There is a similar check in CreateNewBlock() to prevent creating
// invalid blocks, however allowing such transactions into the mempool
// can be exploited as a DoS attack.
if (!CheckInputs(tx, state, view, true, MANDATORY_SCRIPT_VERIFY_FLAGS, true))
return error("AcceptToMemoryPool: : BUG! PLEASE REPORT THIS! ConnectInputs failed against MANDATORY but not STANDARD flags %s", hash.ToString());

// Store transaction in memory
pool.addUnchecked(hash, entry);