From 1929024029d3d789e7daa094d5d599c3d87e43a0 Mon Sep 17 00:00:00 2001
From: Jacob Barthelmeh <jacob@wolfssl.com>
Date: Sat, 29 May 2021 01:10:30 +0700
Subject: [PATCH] fix for getting export buffer size

---
 src/internal.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/internal.c b/src/internal.c
index 8773a7cd1..9c3049c76 100644
--- a/src/internal.c
+++ b/src/internal.c
@@ -1836,7 +1836,7 @@ int wolfSSL_session_export_internal(WOLFSSL* ssl, byte* buf, word32* sz,
 
     WOLFSSL_ENTER("wolfSSL_session_export_internal");
 
-    if (buf == NULL || ssl == NULL) {
+    if (ssl == NULL) {
         WOLFSSL_MSG("unexpected null argument");
         ret = BAD_FUNC_ARG;
     }
@@ -1855,8 +1855,8 @@ int wolfSSL_session_export_internal(WOLFSSL* ssl, byte* buf, word32* sz,
     }
 
     /* check is at least the minimum size needed, TLS cipher states add more */
-    if (ret == 0 && totalLen > *sz) {
-        WOLFSSL_MSG("export buffer was too small");
+    if (ret == 0 && (totalLen > *sz || buf == NULL)) {
+        WOLFSSL_MSG("export buffer was too small or null");
         *sz = totalLen;
 
         /* possible AES state needed */
@@ -1921,7 +1921,7 @@ int wolfSSL_session_export_internal(WOLFSSL* ssl, byte* buf, word32* sz,
         }
     }
 
-    if (ret != 0) {
+    if (ret != 0 && buf != NULL) {
         /*in a fail case clear the buffer which could contain partial key info*/
         XMEMSET(buf, 0, *sz);
     }
@@ -1942,6 +1942,10 @@ int wolfSSL_session_export_internal(WOLFSSL* ssl, byte* buf, word32* sz,
     #endif /* WOLFSSL_SESSION_EXPORT_DEBUG */
     }
 
+    if (ret >= 0) {
+        *sz = ret;
+    }
+
     WOLFSSL_LEAVE("wolfSSL_session_export_internal", ret);
     return ret;
 }