BN_copy now propagates BN_FLG_CONSTTIME

[openssl.git] / crypto / bn / bn_lib.c

diff --git a/crypto/bn/bn_lib.c b/crypto/bn/bn_lib.c
index e61c8706ec4dbab1a01e905ec7d503fcb88d297a..f0a3bf1e3d452a4f8e47c1098656a988a2f0020a 100644 (file)
--- a/crypto/bn/bn_lib.c
+++ b/crypto/bn/bn_lib.c
@@ -267,7 +267,8 @@ static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
     }
 
     assert(b->top <= words);
-    memcpy(a, b->d, sizeof(*a) * b->top);
+    if (b->top > 0)
+        memcpy(a, b->d, sizeof(*a) * b->top);
 
     return a;
 }
@@ -328,7 +329,11 @@ BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
     if (bn_wexpand(a, b->top) == NULL)
         return NULL;
 
-    memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);
+    if (b->top > 0)
+        memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);
+
+    if (BN_get_flags(b, BN_FLG_CONSTTIME) != 0)
+        BN_set_flags(a, BN_FLG_CONSTTIME);
 
     a->top = b->top;
     a->neg = b->neg;