[crypto/bn] BN_consttime_swap: remove superfluous early exit

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18518)

(cherry picked from commit a644cb7c1c19c78e2ca393c8ca36989e7ca61715)

1 files changed, 15 insertions, 0 deletions

diff --git a/test/bntest.c b/test/bntest.c
index c5894c157b..00b9b8cfd8 100644
--- a/test/bntest.c
+++ b/test/bntest.c
@@ -168,6 +168,11 @@ static int test_swap(void)
             || !equalBN("swap", b, c))
         goto err;
 
+    /* regular swap: same pointer */
+    BN_swap(a, a);
+    if (!equalBN("swap with same pointer", a, d))
+        goto err;
+
     /* conditional swap: true */
     cond = 1;
     BN_consttime_swap(cond, a, b, top);
@@ -175,6 +180,11 @@ static int test_swap(void)
             || !equalBN("cswap true", b, d))
         goto err;
 
+    /* conditional swap: true, same pointer */
+    BN_consttime_swap(cond, a, a, top);
+    if (!equalBN("cswap true", a, c))
+        goto err;
+
     /* conditional swap: false */
     cond = 0;
     BN_consttime_swap(cond, a, b, top);
@@ -182,6 +192,11 @@ static int test_swap(void)
             || !equalBN("cswap false", b, d))
         goto err;
 
+    /* conditional swap: false, same pointer */
+    BN_consttime_swap(cond, a, a, top);
+    if (!equalBN("cswap false", a, c))
+        goto err;
+
     /* same tests but checking flag swap */
     BN_set_flags(a, BN_FLG_CONSTTIME);