host-utils: Fix overflow detection in divu128()

The previous code didn't detect overflows if the high 64-bit
of the dividend were equal to the 64-bit divisor. In that case,
64 bits wouldn't be enough to hold the quotient.

Signed-off-by: Luis Pires <luis.pires@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210910112624.72748-2-luis.pires@eldorado.org.br>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

diff --git a/util/host-utils.c b/util/host-utils.c
index 7b93220..a789a11 100644 (file)
--- a/util/host-utils.c
+++ b/util/host-utils.c
@@ -102,7 +102,7 @@ int divu128(uint64_t *plow, uint64_t *phigh, uint64_t divisor)
         *plow  = dlo / divisor;
         *phigh = dlo % divisor;
         return 0;
-    } else if (dhi > divisor) {
+    } else if (dhi >= divisor) {
         return 1;
     } else {