BN_get_word(): return (BN_ULONG)-1 on error rather than BN_MASK2

While the latter is more general in that it also works on 1-complement
achitectures, we don't care about that. Adjust documentation and the
only error check for it in libcrypto.

ok deraadt

3 files changed, 7 insertions, 7 deletions

diff --git a/src/lib/libcrypto/bn/bn_lib.c b/src/lib/libcrypto/bn/bn_lib.c
index 3e451a6191..0326e72c4d 100644
--- a/src/lib/libcrypto/bn/bn_lib.c
+++ b/src/lib/libcrypto/bn/bn_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_lib.c,v 1.94 2025/05/10 05:54:38 tb Exp $ */
+/* $OpenBSD: bn_lib.c,v 1.95 2025/12/15 12:09:46 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -349,7 +349,7 @@ BN_ULONG
 BN_get_word(const BIGNUM *a)
 {
         if (a->top > 1)
-                return BN_MASK2;
+                return (BN_ULONG)-1;
         else if (a->top == 1)
                 return a->d[0];
         /* a->top == 0 */
diff --git a/src/lib/libcrypto/ec/ec_curve.c b/src/lib/libcrypto/ec/ec_curve.c
index 2838965c1e..fda2681704 100644
--- a/src/lib/libcrypto/ec/ec_curve.c
+++ b/src/lib/libcrypto/ec/ec_curve.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ec_curve.c,v 1.59 2025/11/02 13:06:30 tb Exp $ */
+/* $OpenBSD: ec_curve.c,v 1.60 2025/12/15 12:09:46 tb Exp $ */
 /* ====================================================================
  * Copyright (c) 1998-2010 The OpenSSL Project.  All rights reserved.
  *
@@ -1392,7 +1392,7 @@ ec_curve_from_group(const EC_GROUP *group)
         if ((cofactor = EC_GROUP_get0_cofactor(group)) != NULL) {
                 BN_ULONG cofactor_word;
 
-                if ((cofactor_word = BN_get_word(cofactor)) == BN_MASK2)
+                if ((cofactor_word = BN_get_word(cofactor)) == (BN_ULONG)-1)
                         goto err;
                 if (cofactor_word > INT_MAX)
                         goto err;
diff --git a/src/lib/libcrypto/man/BN_zero.3 b/src/lib/libcrypto/man/BN_zero.3
index 18a31a1080..d94a2a10da 100644
--- a/src/lib/libcrypto/man/BN_zero.3
+++ b/src/lib/libcrypto/man/BN_zero.3
@@ -1,4 +1,4 @@
-.\" $OpenBSD: BN_zero.3,v 1.15 2025/06/14 06:48:47 tb Exp $
+.\" $OpenBSD: BN_zero.3,v 1.16 2025/12/15 12:09:46 tb Exp $
 .\" full merge up to: OpenSSL a528d4f0 Oct 27 13:40:11 2015 -0400
 .\" selective merge up to: OpenSSL b713c4ff Jan 22 14:41:09 2018 -0500
 .\"
@@ -67,7 +67,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 .\" OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: June 14 2025 $
+.Dd $Mdocdate: December 15 2025 $
 .Dt BN_ZERO 3
 .Os
 .Sh NAME
@@ -132,7 +132,7 @@ This constant is useful for comparisons and assignments.
 .Fn BN_get_word
 returns the value
 .Fa a ,
-or a number with all bits set if
+or (BN_ULONG)\-1 if
 .Fa a
 cannot be represented as a
 .Vt BN_ULONG .