refactor: Avoid unsigned integer overflow in script/interpreter.cpp

Although unsigned integer overflow is not undefined behavior, it's preferable to eliminate the need for a UBSan suppression for it.
bitcoin · Mar 8, 2024 · 754ba68 · 754ba68
1 parent 54172c6
commit 754ba68
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Showing 2 changed files with 2 additions and 3 deletions.
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
@@ -51,8 +51,8 @@ bool CastToBool(const valtype& vch)
  * Script is a stack machine (like Forth) that evaluates a predicate
  * returning a bool indicating valid or not.  There are no loops.
  */
-#define stacktop(i)  (stack.at(stack.size()+(i)))
-#define altstacktop(i)  (altstack.at(altstack.size()+(i)))
+#define stacktop(i) (stack.at(stack.size() - (-(i))))
+#define altstacktop(i) (altstack.at(altstack.size() - (-(i))))
 static inline void popstack(std::vector<valtype>& stack)
 {
     if (stack.empty())

diff --git a/test/sanitizer_suppressions/ubsan b/test/sanitizer_suppressions/ubsan
@@ -55,7 +55,6 @@ unsigned-integer-overflow:MurmurHash3
 unsigned-integer-overflow:CBlockPolicyEstimator::processBlockTx
 unsigned-integer-overflow:TxConfirmStats::EstimateMedianVal
 unsigned-integer-overflow:prevector.h
-unsigned-integer-overflow:EvalScript
 unsigned-integer-overflow:xoroshiro128plusplus.h
 implicit-integer-sign-change:CBlockPolicyEstimator::processBlockTx
 implicit-integer-sign-change:SetStdinEcho