From 64a9e6f7c48b495ef323c8f9d65e0775284c5f80 Mon Sep 17 00:00:00 2001
From: Sean Parkinson <sean@wolfssl.com>
Date: Wed, 16 Oct 2024 14:08:55 +1000
Subject: [PATCH] BN API: fix BN_bin2bn to handle NULL data properly

BN_bin2bn was freeing the BN and returning it.
Added test for this.
---
 src/ssl_bn.c | 4 +++-
 tests/api.c  | 5 +++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/ssl_bn.c b/src/ssl_bn.c
index e45e19da50..74eadcead2 100644
--- a/src/ssl_bn.c
+++ b/src/ssl_bn.c
@@ -516,12 +516,14 @@ WOLFSSL_BIGNUM* wolfSSL_BN_bin2bn(const unsigned char* data, int len,
                 ret = NULL;
             }
             else {
-                /* Don't free bn as we may be returning it. */
+                /* Don't free bn as we are returning it. */
                 bn = NULL;
             }
         }
         else if (data == NULL) {
             wolfSSL_BN_zero(ret);
+            /* Don't free bn as we are returning it. */
+            bn = NULL;
         }
     }
 
diff --git a/tests/api.c b/tests/api.c
index fc68a44715..eca756cfd5 100644
--- a/tests/api.c
+++ b/tests/api.c
@@ -61606,6 +61606,11 @@ static int test_wolfSSL_BN_enc_dec(void)
     ExpectNull(BN_bn2dec(NULL));
     ExpectNull(BN_bn2dec(&emptyBN));
 
+    ExpectNotNull(c = BN_bin2bn(NULL, 0, NULL));
+    BN_clear(c);
+    BN_free(c);
+    c = NULL;
+
     ExpectNotNull(BN_bin2bn(NULL, sizeof(binNum), a));
     BN_free(a);
     ExpectNotNull(a = BN_new());