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Firefox · SpiderMonkey

CVE-2025-1933

Logic Error in SpiderMonkey
High firefox Logic Error 🔧 Commit mapped

Overview

High
Severity
—
CVSS
No
Exploited ITW
Fixed
Fix Status
Impacthigh
DescriptionOn 64-bit CPUs, when the JIT compiles WASM i32 return values they can pick up bits from left over memory. This can potentially cause them to be treated as a different type.
ComponentSpiderMonkey
Bug ClassLogic Error
Tracker1946004
Fix commit4c82b20fcda2 (firefox) +3/-1
CISA KEVNot listed
CreditedXiangwei Zhang and kkdong of Tencent Security YUNDING LAB
Disclosed2025-03-04

Files Changed

  • js/src/wasm/WasmStubs.cpp

Patch

view commit
diff --git a/js/src/wasm/WasmStubs.cpp b/js/src/wasm/WasmStubs.cpp
index a7e101bd5b3..8d821c40452 100644
--- a/js/src/wasm/WasmStubs.cpp
+++ b/js/src/wasm/WasmStubs.cpp
@@ -1241,7 +1241,9 @@ static bool GenerateJitEntry(MacroAssembler& masm, size_t funcExportIndex,
     switch (results[0].kind()) {
       case ValType::I32:
         GenPrintIsize(DebugChannel::Function, masm, ReturnReg);
-        // No widening is required, as the value is boxed.
+#ifdef JS_64BIT
+        masm.widenInt32(ReturnReg);
+#endif
         masm.boxNonDouble(JSVAL_TYPE_INT32, ReturnReg, JSReturnOperand);
         break;
       case ValType::F32: {
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