1 files changed, 4 insertions, 1 deletions

diff --git a/src/lib/libcrypto/bn/bn_lib.c b/src/lib/libcrypto/bn/bn_lib.c
index 49cc6662db..980c9b5457 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 1.78 2023/03/27 10:25:02 tb Exp $ */
+/* $OpenBSD: bn_lib.c,v 1.79 2023/03/31 19:39:15 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -379,6 +379,9 @@ BN_copy(BIGNUM *a, const BIGNUM *b)
         memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);
 #endif
 
+        /* Copy constant time flag from b, but make it sticky on a. */
+        a->flags |= b->flags & BN_FLG_CONSTTIME;
+
         a->top = b->top;
         a->neg = b->neg;
         return (a);