Fix debug-info: prevent invalid access in the original event_context

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/plugins/lttng-utils/copy.c b/plugins/lttng-utils/copy.c
index 68ea1237803f1d49e546f3d2fa6a899b66fe3a34..482f372ad2e7208099d3d520b3a65e9dbac2bc55 100644 (file)
--- a/plugins/lttng-utils/copy.c
+++ b/plugins/lttng-utils/copy.c
@@ -1245,7 +1245,8 @@ int copy_set_debug_info_stream_event_context(FILE *err,
                struct debug_info *debug_info,
                struct debug_info_component *component)
 {
-       struct bt_ctf_field_type *writer_event_context_type = NULL;
+       struct bt_ctf_field_type *writer_event_context_type = NULL,
+                                *event_context_type = NULL;
        struct bt_ctf_field *writer_event_context = NULL;
        struct bt_ctf_field *field = NULL, *copy_field = NULL, *debug_field = NULL;
        struct bt_ctf_field_type *field_type = NULL;
@@ -1265,6 +1266,13 @@ int copy_set_debug_info_stream_event_context(FILE *err,
                goto error;
        }
 
+       event_context_type = bt_ctf_field_get_type(event_context);
+       if (!event_context_type) {
+               fprintf(err, "[error] %s in %s:%d\n", __func__,
+                               __FILE__, __LINE__);
+               goto error;
+       }
+
        /*
         * If it is not a structure, we did not modify it to add the debug info
         * fields, so just assign it as is.
@@ -1287,12 +1295,15 @@ int copy_set_debug_info_stream_event_context(FILE *err,
                        goto error;
                }
 
-               field = bt_ctf_field_structure_get_field_by_index(event_context, i);
+               /*
+                * Prevent illegal access in the event_context.
+                */
+               if (i < bt_ctf_field_type_structure_get_field_count(event_context_type)) {
+                       field = bt_ctf_field_structure_get_field_by_index(event_context, i);
+               }
                /*
                 * The debug_info field, only exists in the writer event or
                 * if it was set by a earlier pass of the debug_info plugin.
-                *
-                * FIXME: are we replacing an exisiting debug_info struct here ??
                 */
                if (!strcmp(field_name, component->arg_debug_info_field_name) &&
                                !field) {
@@ -1338,6 +1349,7 @@ int copy_set_debug_info_stream_event_context(FILE *err,
 error:
        ret = -1;
 end:
+       bt_put(event_context_type);
        bt_put(writer_event_context_type);
        bt_put(writer_event_context);
        bt_put(field);