fix #2

1. Fix the memory corruption caused by improper space allocation
2. Fix iov access, need indexing, otherwise its the same element

src/ucp/core/ucp_request.c

@@ -283,9 +283,9 @@ UCS_PROFILE_FUNC(ucs_status_t, ucp_request_memory_reg,
             goto err;
         }
         for (iov_it = 0; iov_it < iovcnt; ++iov_it) {
-            size_t iov_len = ucp_dt_extent(iov->dt, iov->count, NULL, NULL);
+            size_t iov_len = ucp_dt_extent(iov[iov_it].dt, iov[iov_it].count, NULL, NULL);
             if (iov_len) {
-                status = uct_md_mem_reg(uct_md, iov->buffer, iov_len, 0,
+                status = uct_md_mem_reg(uct_md, iov[iov_it].buffer, iov_len, 0,
                                         &memh[iov_it]);
                 if (status != UCS_OK) {
                     /* unregister previously registered memory */

src/ucp/proto/proto_dt.c

@@ -149,28 +149,17 @@ ucs_status_t ucp_dt_reusable_create(uct_ep_h ep, void *buffer, size_t length,
     size_t uct_iovcnt = 0;
     size_t length_it = 0;
 
-    dt_ex->reusable.nc_iov = ucs_malloc(sizeof(uct_iov_t) * uct_iovcnt, "reusable_iov");
-    if (!dt_ex->reusable.nc_iov) {
-        return UCS_ERR_NO_MEMORY;
-    }
-
     switch (datatype & UCP_DATATYPE_CLASS_MASK) {
     case UCP_DATATYPE_STRIDE_R:
         uct_iovcnt = ucp_dt_count_uct_iov(datatype, 1, buffer, NULL); // TODO: "half-state"?
-        dt_ex->reusable.length = ucp_dt_stride_copy_uct(dt_ex->reusable.nc_iov,
-                &dt_ex->reusable.nc_iovcnt, uct_iovcnt, state, buffer, datatype, length);
         break;
-
     case UCP_DATATYPE_IOV_R:
         iov_it = buffer;
         while (length_it < length) {
             length_it += ucp_dt_length(iov_it->dt, iov_it->count, iov_it->buffer, NULL);
             uct_iovcnt += ucp_dt_count_uct_iov(iov_it->dt, iov_it->count, iov_it->buffer, NULL);
             iov_it++;
         }
-
-        dt_ex->reusable.length = ucp_dt_iov_copy_uct(dt_ex->reusable.nc_iov,
-                &dt_ex->reusable.nc_iovcnt, uct_iovcnt, state, buffer, datatype, length);
         break;
 
     default:
@@ -179,6 +168,13 @@ ucs_status_t ucp_dt_reusable_create(uct_ep_h ep, void *buffer, size_t length,
         return UCS_ERR_INVALID_PARAM;
     }
 
+    dt_ex->reusable.nc_iov = ucs_malloc(sizeof(uct_iov_t) * uct_iovcnt, "reusable_iov");
+    if (!dt_ex->reusable.nc_iov) {
+        return UCS_ERR_NO_MEMORY;
+    }
+    dt_ex->reusable.length = ucp_dt_iov_copy_uct(dt_ex->reusable.nc_iov,
+            &dt_ex->reusable.nc_iovcnt, uct_iovcnt, state, buffer, datatype, length);
+
     dt_ex->reusable.nc_comp.func = ucp_dt_reusable_completion;
     return uct_ep_mem_reg_nc(ep, dt_ex->reusable.nc_iov, dt_ex->reusable.nc_iovcnt,
             &dt_ex->reusable.nc_md, &dt_ex->reusable.nc_memh, &dt_ex->reusable.nc_comp);