Correctly access the communicator name is MSGQ.

We transformed the communicator c_name field from an array into a
pointer and fialed to update the MSGQ accessors to the field.

Thanks @david-edwards-linaro for the report and the initial patch.

Fixes #12063.

Signed-off-by: George Bosilca <bosilca@icl.utk.edu>

Author: bosilca

ompi/debuggers/ompi_mpihandles_dll.c

@@ -7,7 +7,9 @@
  * Copyright (c) 2012-2013 Inria.  All rights reserved.
  * Copyright (c) 2016      Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
- * Copyright (c) 2017 IBM Corp.  All rights reserved.
+ * Copyright (c) 2017      IBM Corp.  All rights reserved.
+ * Copyright (c) 2023      NVIDIA Corporation. All rights reserved.
+ * Copyright (c) 2023      Jeffrey M. Squyres.  All rights reserved.
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -458,8 +460,21 @@ int mpidbg_comm_query(mqs_image *image, mqs_image_info *image_info,
     (*info)->comm_c_handle = c_comm;
 
     printf("mpidbg_comm_query: %p\n", (void*) c_comm);
-    mqs_fetch_data(process, c_comm + i_info->ompi_communicator_t.offset.c_name,
+    mqs_taddr_t name_addr = ompi_fetch_pointer( process,
+                                                c_comm + i_info->ompi_communicator_t.offset.c_name,
+                                                p_info );
+    mqs_fetch_data(process, name_addr,
                    MPIDBG_MAX_OBJECT_NAME, (*info)->comm_name);
+    (*info)->comm_name[MPIDBG_MAX_OBJECT_NAME-1] = '\0';
+    /* Defensively zero anything beyond the actual name.
+
+       We know that MPIDBG_MAX_OBJECT_NAME == MPI_MAX_OBJECT_NAME (per
+       mpihandles_interface.h), and OMPI *guarantees* that
+       (*info)->comm_name will be both \0-terminated, and have a
+       maximum of (MPI_MAX_OBJECT_NAME-1) non-NULL characters.  So the
+       memset length expression below is guaranted be >=0. */
+    memset((*info)->comm_name + strlen((*info)->comm_name), 0,
+           MPIDBG_MAX_OBJECT_NAME - 1 - strlen((*info)->comm_name));
 
     /* Get this process' rank in the comm */
     (*info)->comm_rank = ompi_fetch_int(process,

ompi/debuggers/ompi_msgq_dll.c

@@ -10,6 +10,8 @@
  * Copyright (c) 2016      Intel, Inc. All rights reserved.
  * Copyright (c) 2016      Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
+ * Copyright (c) 2023      NVIDIA Corporation. All rights reserved.
+ * Copyright (c) 2023      Jeffrey M. Squyres.  All rights reserved.
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -682,8 +684,18 @@ static int rebuild_communicator_list (mqs_process *proc)
                                     p_info );
             old->group = find_or_create_group( proc, group_base );
         }
-        mqs_fetch_data( proc, comm_ptr + i_info->ompi_communicator_t.offset.c_name,
-                        64, old->comm_info.name );
+        mqs_taddr_t name_addr = ompi_fetch_pointer( proc,
+                                                    comm_ptr + i_info->ompi_communicator_t.offset.c_name,
+                                                    p_info );
+        /* c_name can be up to MPI_MAX_OBJECT_NAME bytes, but we only
+         * copy the first (sizeof(old->comm_info.name)-1) here.  Make
+         * sure the string is correctly terminated. */
+        size_t target_size = sizeof(old->comm_info.name);
+        mqs_fetch_data( proc, name_addr, target_size, old->comm_info.name );
+        old->comm_info.name[target_size - 1] = '\0';
+        /* Defensively zero anything beyond the actual name */
+        size_t src_strlen = strlen(old->comm_info.name);
+        memset(old->comm_info.name + src_strlen, 0, target_size - 1 - src_strlen);
 
         if( NULL != old->group ) {
             old->comm_info.size = old->group->entries;
@@ -1156,8 +1168,9 @@ static int fetch_request( mqs_process *proc, mpi_process_info *p_info,
                                ompi_datatype + i_info->ompi_datatype_t.offset.size,
                                p_info );
         /* Be user friendly, show the datatype name */
+        size_t data_name_size = sizeof(data_name);
         mqs_fetch_data( proc, ompi_datatype + i_info->ompi_datatype_t.offset.name,
-                        64, data_name );
+                        data_name_size, data_name );
         if( '\0' != data_name[0] ) {
             // res->extra_text[x] is only 64 chars long -- same as
             // data_name.  If you try to snprintf it into
@@ -1171,6 +1184,11 @@ static int fetch_request( mqs_process *proc, mpi_process_info *p_info,
                       (int)res->desired_length);
             snprintf( (char*)res->extra_text[2], 64, "%s",
                       data_name );
+        } else {
+            data_name[data_name_size - 1] = '\0';
+            /* Be nice and zero anything beyond the actual name */
+            size_t data_name_strlen = strlen(data_name);
+            memset(data_name + data_name_strlen, 0, data_name_size - 1 - data_name_strlen);
         }
         /* And now compute the real length as specified by the user */
         res->desired_length *=