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Avoid double free in simplicity pointer when copying PrecomputedTrans… #1425

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4 changes: 2 additions & 2 deletions src/script/interpreter.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -2669,7 +2669,7 @@ void PrecomputedTransactionData::Init(const T& txTo, std::vector<CTxOut>&& spent
simplicityRawTx.version = txTo.nVersion;
simplicityRawTx.lockTime = txTo.nLockTime;

m_simplicity_tx_data = simplicity_elements_mallocTransaction(&simplicityRawTx);
m_simplicity_tx_data = SimplicityTransactionUniquePtr(simplicity_elements_mallocTransaction(&simplicityRawTx));

m_bip341_taproot_ready = true;
}
Expand Down Expand Up @@ -3121,7 +3121,7 @@ bool GenericTransactionSignatureChecker<T>::CheckSimplicity(const valtype& progr

assert(txdata->m_simplicity_tx_data);
assert(simplicityTapEnv);
if (!simplicity_elements_execSimplicity(&error, 0, txdata->m_simplicity_tx_data, nIn, simplicityTapEnv, txdata->m_hash_genesis_block.data(), budget, 0, program.data(), program.size(), witness.data(), witness.size())) {
if (!simplicity_elements_execSimplicity(&error, 0, txdata->m_simplicity_tx_data.get(), nIn, simplicityTapEnv, txdata->m_hash_genesis_block.data(), budget, 0, program.data(), program.size(), witness.data(), witness.size())) {
assert(!"simplicity_elements_execSimplicity internal error");
}
simplicity_elements_freeTapEnv(simplicityTapEnv);
Expand Down
14 changes: 10 additions & 4 deletions src/script/interpreter.h
Original file line number Diff line number Diff line change
Expand Up @@ -169,9 +169,18 @@ enum : uint32_t {

bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned int flags, ScriptError* serror);

struct SimplicityTransactionDeleter
{
void operator()(transaction* ptr)
{
simplicity_elements_freeTransaction(ptr);
}
};
using SimplicityTransactionUniquePtr = std::unique_ptr<transaction, SimplicityTransactionDeleter>;

struct PrecomputedTransactionData
{
transaction* m_simplicity_tx_data = nullptr;
SimplicityTransactionUniquePtr m_simplicity_tx_data;
// BIP341 precomputed data.
// These are single-SHA256, see https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki#cite_note-15.
uint256 m_prevouts_single_hash;
Expand Down Expand Up @@ -221,9 +230,6 @@ struct PrecomputedTransactionData

template <class T>
explicit PrecomputedTransactionData(const T& tx);
~PrecomputedTransactionData() {
simplicity_elements_freeTransaction(m_simplicity_tx_data);
}
};

enum class SigVersion
Expand Down
4 changes: 2 additions & 2 deletions src/test/fuzz/simplicity.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -204,13 +204,13 @@ FUZZ_TARGET_INIT(simplicity, initialize_simplicity)
PrecomputedTransactionData txdata{GENESIS_HASH};
std::vector<CTxOut> spent_outs_copy{spent_outs};
txdata.Init(mtx, std::move(spent_outs_copy));
assert(txdata.m_simplicity_tx_data != NULL);
assert(txdata.m_simplicity_tx_data);

// 4. Main test
unsigned char imr_out[32];
unsigned char *imr = mtx.vin[0].prevout.hash.data()[2] & 2 ? imr_out : NULL;

const transaction* tx = txdata.m_simplicity_tx_data;
const transaction* tx = txdata.m_simplicity_tx_data.get();
tapEnv* taproot = simplicity_elements_mallocTapEnv(&simplicityRawTap);
simplicity_elements_execSimplicity(&error, imr, tx, nIn, taproot, GENESIS_HASH.data(), budget, amr, prog_bytes.data(), prog_bytes.size(), wit_bytes.data(), wit_bytes.size());

Expand Down
2 changes: 1 addition & 1 deletion src/test/fuzz/simplicity_tx.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -217,7 +217,7 @@ FUZZ_TARGET_INIT(simplicity_tx, initialize_simplicity_tx)
// that we will allocate Simplicity data. The check for whether to do this is very
// lax: is this a 34-byte scriptPubKey that starts with OP_1 and does it have a
// nonempty witness.
assert(txdata.m_simplicity_tx_data != NULL);
assert(txdata.m_simplicity_tx_data);
}

const CTransaction tx{mtx};
Expand Down