From: https://github.com/libssh2/libssh2/commit/e7e1312b0cbfa643e2f8bf5f2036ce5147ed797d
From: bagder <daniel@haxx.se>
Date: 21 Mar 2022 10:11 -0800
Subject: misc/libssh2_copy_string: avoid malloc zero bytes #686

Notes:
* Avoid the inconsistent malloc return code for malloc(0)

--- libssh2-1.10.0/src/misc.c	2019-09-13 14:39:11.000000000 +0800
+++ libssh2-1.10.0/src/misc.c	2022-09-29 18:27:13.604424483 +0800
@@ -794,12 +794,18 @@
         return -1;
     }
 
-    *outbuf = LIBSSH2_ALLOC(session, str_len);
-    if(*outbuf) {
-        memcpy(*outbuf, str, str_len);
+    if(str_len) {
+        *outbuf = LIBSSH2_ALLOC(session, str_len);
+        if(*outbuf) {
+            memcpy(*outbuf, str, str_len);
+        }
+        else {
+            return -1;
+        }
     }
     else {
-        return -1;
+	*outlen = 0;
+        *outbuf = NULL;
     }
 
     if(outlen)