range check in IsLosslessFloat to avoid undefined double->float cast

efidler · efidler · commit 875a9e159938 · 2016-06-01T12:06:20.000-04:00
UBSAN gave in Value.IsLosslessFloat:
include/rapidjson/document.h:981:38: runtime error: value 3.40282e+38 is outside the range of representable values of type 'float'
diff --git a/include/rapidjson/document.h b/include/rapidjson/document.h
@@ -978,6 +978,8 @@ class GenericValue {
     bool IsLosslessFloat() const {
         if (!IsNumber()) return false;
         double a = GetDouble();
+        if (a < static_cast<double>(-3.4028234e38f) || a > static_cast<double>(3.4028234e38f))
+            return false;
         double b = static_cast<double>(static_cast<float>(a));
         return a >= b && a <= b;    // Prevent -Wfloat-equal
     }

Original file line number	Diff line number	Diff line change
`@@ -978,6 +978,8 @@ class GenericValue {`
`978`	`978`	`bool IsLosslessFloat() const {`
`979`	`979`	`if (!IsNumber()) return false;`
`980`	`980`	`double a = GetDouble();`
	`981`	`+ if (a < static_cast<double>(-3.4028234e38f) \|\| a > static_cast<double>(3.4028234e38f))`
	`982`	`+ return false;`
`981`	`983`	`double b = static_cast<double>(static_cast<float>(a));`
`982`	`984`	`return a >= b && a <= b; // Prevent -Wfloat-equal`
`983`	`985`	`}`