Merge pull request #1843 from Exiv2/mergify/bp/main/pr-1840

Check that the float is within the range of an int before casting (backport #1840)

src/types.cpp

@@ -36,6 +36,7 @@
 #include <sstream>
 #include <utility>
 #include <cctype>
+#include <climits>
 #include <ctime>
 #include <cstdio>
 #include <cstdlib>
@@ -670,27 +671,28 @@ namespace Exiv2 {
 
     Rational floatToRationalCast(float f)
     {
-#if defined(_MSC_VER) && _MSC_VER < 1800
-        if (!_finite(f)) {
-#else
-        if (!std::isfinite(f)) {
-#endif
-            return {f > 0 ? 1 : -1, 0};
+
+        // Convert f to double because it simplifies the "in_range" check
+        // below. (INT_MAX can be represented accurately as a double, but
+        // gets rounded when it's converted to float.)
+        const double d = f;
+        const bool in_range = INT_MIN <= d && d <= INT_MAX;
+        if (!in_range) {
+            return {d > 0 ? 1 : -1, 0};
         }
         // Beware: primitive conversion algorithm
         int32_t den = 1000000;
-        const long f_as_long = static_cast<long>(f);
-        if (Safe::abs(f_as_long) > 2147) {
+        const long d_as_long = static_cast<long>(d);
+        if (Safe::abs(d_as_long) > 2147) {
             den = 10000;
         }
-        if (Safe::abs(f_as_long) > 214748) {
+        if (Safe::abs(d_as_long) > 214748) {
             den = 100;
         }
-        if (Safe::abs(f_as_long) > 21474836) {
+        if (Safe::abs(d_as_long) > 21474836) {
             den = 1;
         }
-        const float rnd = f >= 0 ? 0.5F : -0.5F;
-        const auto nom = static_cast<int32_t>(f * den + rnd);
+        const auto nom = static_cast<int32_t>(std::round(d * den));
         const int32_t g = gcd(nom, den);
 
         return {nom / g, den / g};

tests/bugfixes/github/test_issue_1838.py

@@ -0,0 +1,17 @@
+# -*- coding: utf-8 -*-
+
+from system_tests import CaseMeta, path, check_no_ASAN_UBSAN_errors
+
+class FloatToRationalCastOutOfRange(metaclass=CaseMeta):
+    """
+    Test for the bug described in:
+    https://github.com/Exiv2/exiv2/issues/1838
+    """
+    url = "https://github.com/Exiv2/exiv2/issues/1838"
+
+    filename = path("$data_path/issue_1838_poc.crw")
+    commands = ["$exiv2 $filename"]
+    stderr = [""]
+    retval = [0]
+
+    compare_stdout = check_no_ASAN_UBSAN_errors