feefrac: avoid integer overflow in temporary

sipa · sipa · commit 5cb1241814b9 · 2025-04-17T17:37:35.000-04:00
diff --git a/src/test/feefrac_tests.cpp b/src/test/feefrac_tests.cpp
@@ -148,6 +148,8 @@ BOOST_AUTO_TEST_CASE(feefrac_operators)
     FeeFrac max_fee2{1, 1};
     BOOST_CHECK(max_fee >= max_fee2);
 
+    // Test for integer overflow issue (https://github.com/bitcoin/bitcoin/issues/32294)
+    BOOST_CHECK_EQUAL((FeeFrac{0x7ffffffdfffffffb, 0x7ffffffd}.EvaluateFeeDown(0x7fffffff)), 0x7fffffffffffffff);
 }
 
 BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/util/feefrac.h b/src/util/feefrac.h
@@ -96,7 +96,7 @@ struct FeeFrac
         int64_t quot = n / d;
         int32_t mod = n % d;
         // Correct result if the / operator above rounded in the wrong direction.
-        return quot + (mod > 0) - (mod && round_down);
+        return quot + ((mod > 0) - (mod && round_down));
     }
 #else
     static constexpr auto Mul = MulFallback;

Original file line number	Diff line number	Diff line change
`@@ -148,6 +148,8 @@ BOOST_AUTO_TEST_CASE(feefrac_operators)`
`148`	`148`	`FeeFrac max_fee2{1, 1};`
`149`	`149`	`BOOST_CHECK(max_fee >= max_fee2);`
`150`	`150`
	`151`	`+ // Test for integer overflow issue (https://github.com/bitcoin/bitcoin/issues/32294)`
	`152`	`+ BOOST_CHECK_EQUAL((FeeFrac{0x7ffffffdfffffffb, 0x7ffffffd}.EvaluateFeeDown(0x7fffffff)), 0x7fffffffffffffff);`
`151`	`153`	`}`
`152`	`154`
`153`	`155`	`BOOST_AUTO_TEST_SUITE_END()`
Original file line number	Diff line number	Diff line change
`@@ -96,7 +96,7 @@ struct FeeFrac`
`96`	`96`	`int64_t quot = n / d;`
`97`	`97`	`int32_t mod = n % d;`
`98`	`98`	`// Correct result if the / operator above rounded in the wrong direction.`
`99`		`- return quot + (mod > 0) - (mod && round_down);`
	`99`	`+ return quot + ((mod > 0) - (mod && round_down));`
`100`	`100`	`}`
`101`	`101`	`#else`
`102`	`102`	`static constexpr auto Mul = MulFallback;`