* bignum.c (rb_big_pow): refine overflow check. [ruby-dev:31242]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@12813 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 3 insertions, 1 deletions

diff --git a/bignum.c b/bignum.c
index 5763e8c72f..16fbe86527 100644
--- a/bignum.c
+++ b/bignum.c
@@ -1755,8 +1755,10 @@ rb_big_pow(x, y)
 	if (yy > 0) {
 	    VALUE z = 0;
 	    long mask;
+	    const long BIGLEN_LIMIT = 1024*1024 / SIZEOF_BDIGITS;
 
-	    if (RBIGNUM(x)->len * SIZEOF_BDIGITS * yy > 1024*1024) {
+	    if ((RBIGNUM(x)->len > BIGLEN_LIMIT) ||
+		(RBIGNUM(x)->len > BIGLEN_LIMIT / yy)) {
 		rb_warn("in a**b, b may be too big");
 		d = (double)yy;
 		break;