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add stricter bounds checks for bytecode parsing #6

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Merged
mooorex merged 1 commit into from
May 29, 2025
Merged

add stricter bounds checks for bytecode parsing #6

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25 changes: 18 additions & 7 deletions src/transaction/deserialize.c
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Original file line number Diff line number Diff line change
Expand Up @@ -229,21 +229,26 @@ static parser_status_e transaction_deserialize_contract(buffer_t *buf, transacti

size_t os = buf->offset;
switch (tx->header.tx_type) {
case 0xd1:
case 0xd1: {
if(!buffer_can_read(buf, ARRAY_LENGTH(OPCODE_END) + ADDRESS_SCRIPT_HASH_LEN + 1)) {
return PARSING_BYTECODE_WRONG;
}
if (buf->ptr[buf->size - ARRAY_LENGTH(OPCODE_END) - ADDRESS_SCRIPT_HASH_LEN - 1] !=
OPCODE_APPCALL[0]) { //'n' for the native contract
tx->contract.type = NATIVE_CONTRACT;
if ((!buffer_seek_set(buf, buf->size - NATIVE_CONTRACT_CONSTANT_LENGTH) ||
!parse_address(buf, true, &(tx->contract.addr)) ||
!parse_check_constant(buf, OPCODE_SYSCALL, ARRAY_LENGTH(OPCODE_SYSCALL)) ||
!parse_check_constant(buf, NATIVE_INVOKE, ARRAY_LENGTH(NATIVE_INVOKE)) ||
!parse_check_constant(buf, OPCODE_END, ARRAY_LENGTH(OPCODE_END))) ||
if (!buffer_can_read(buf, NATIVE_CONTRACT_CONSTANT_LENGTH) ||
!buffer_seek_set(buf, buf->size - NATIVE_CONTRACT_CONSTANT_LENGTH) ||
!parse_address(buf, true, &(tx->contract.addr)) ||
!parse_check_constant(buf, OPCODE_SYSCALL, ARRAY_LENGTH(OPCODE_SYSCALL)) ||
!parse_check_constant(buf, NATIVE_INVOKE, ARRAY_LENGTH(NATIVE_INVOKE)) ||
!parse_check_constant(buf, OPCODE_END, ARRAY_LENGTH(OPCODE_END)) ||
buf->offset != buf->size || !buffer_seek_set(buf, os)) {
return PARSING_BYTECODE_WRONG;
}
} else { // 0x67 for the neovm contract
tx->contract.type = NEOVM_CONTRACT;
if (!buffer_seek_set(buf, buf->size - NEOVM_CONTRACT_CONSTANT_LENGTH) ||
if (!buffer_can_read(buf, NEOVM_CONTRACT_CONSTANT_LENGTH) ||
!buffer_seek_set(buf, buf->size - NEOVM_CONTRACT_CONSTANT_LENGTH) ||
!parse_check_constant(buf, OPCODE_APPCALL, ARRAY_LENGTH(OPCODE_APPCALL)) ||
!parse_address(buf, false, &(tx->contract.addr)) ||
!parse_check_constant(buf, OPCODE_END, ARRAY_LENGTH(OPCODE_END)) ||
Expand All @@ -252,6 +257,7 @@ static parser_status_e transaction_deserialize_contract(buffer_t *buf, transacti
}
}
break;
}
case 0xd2:
tx->contract.type = WASMVM_CONTRACT;
if (!parse_address(buf, false, &(tx->contract.addr))) {
Expand Down Expand Up @@ -297,6 +303,11 @@ static parser_status_e transaction_deserialize_method(buffer_t *buf, transaction
return PARSING_BYTECODE_WRONG;
}

// Validate sEnd to prevent underflow
if (sEnd < sBegin || sEnd > buf->size || sEnd < sBegin + (ARRAY_LENGTH(OPCODE_PACK) - 2)) {
return PARSING_BYTECODE_WRONG;
}

size_t method_intent_length = 0;
size_t cur = 0;
for (size_t i = sEnd - (ARRAY_LENGTH(OPCODE_PACK) - 2); i >= sBegin; i--) {
Expand Down
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