Fix: app contexts: do not leak app context name, event field, context field

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I4f0655034d37024a3fa024a3b45f0168a3aeb9cd

diff --git a/liblttng-ust/lttng-context-provider.c b/liblttng-ust/lttng-context-provider.c
index bc2b23e6ec8c105b6afd1a6eb0bb5b320d85a777..c70da2089992a71a102d5faf3d6438039b044e7e 100644 (file)
--- a/liblttng-ust/lttng-context-provider.c
+++ b/liblttng-ust/lttng-context-provider.c
@@ -26,6 +26,12 @@ struct lttng_ust_registered_context_provider {
        struct cds_hlist_node node;
 };
 
+struct lttng_ust_app_ctx {
+       char *name;
+       struct lttng_ust_event_field *event_field;
+       struct lttng_ust_type_common *type;
+};
+
 #define CONTEXT_PROVIDER_HT_BITS       12
 #define CONTEXT_PROVIDER_HT_SIZE       (1U << CONTEXT_PROVIDER_HT_BITS)
 struct context_provider_ht {
@@ -118,6 +124,16 @@ end:
        free(reg_provider);
 }
 
+static void destroy_app_ctx(void *priv)
+{
+       struct lttng_ust_app_ctx *app_ctx = (struct lttng_ust_app_ctx *) priv;
+
+       free(app_ctx->name);
+       free(app_ctx->event_field);
+       free(app_ctx->type);
+       free(app_ctx);
+}
+
 /*
  * Called with ust mutex held.
  * Add application context to array of context, even if the application
@@ -130,25 +146,22 @@ int lttng_ust_add_app_context_to_ctx_rcu(const char *name,
                struct lttng_ust_ctx **ctx)
 {
        const struct lttng_ust_context_provider *provider;
-       struct lttng_ust_ctx_field *new_field = NULL;
+       struct lttng_ust_ctx_field new_field = { 0 };
        struct lttng_ust_event_field *event_field = NULL;
        struct lttng_ust_type_common *type = NULL;
+       struct lttng_ust_app_ctx *app_ctx = NULL;
+       char *ctx_name;
        int ret;
 
        if (*ctx && lttng_find_context(*ctx, name))
                return -EEXIST;
-       new_field = zmalloc(sizeof(struct lttng_ust_ctx_field));
-       if (!new_field) {
-               ret = -ENOMEM;
-               goto error_field_alloc;
-       }
        event_field = zmalloc(sizeof(struct lttng_ust_event_field));
        if (!event_field) {
                ret = -ENOMEM;
                goto error_event_field_alloc;
        }
-       event_field->name = strdup(name);
-       if (!event_field->name) {
+       ctx_name = strdup(name);
+       if (!ctx_name) {
                ret = -ENOMEM;
                goto error_field_name_alloc;
        }
@@ -157,44 +170,48 @@ int lttng_ust_add_app_context_to_ctx_rcu(const char *name,
                ret = -ENOMEM;
                goto error_field_type_alloc;
        }
+       app_ctx = zmalloc(sizeof(struct lttng_ust_app_ctx));
+       if (!app_ctx) {
+               ret = -ENOMEM;
+               goto error_app_ctx_alloc;
+       }
+       event_field->name = ctx_name;
        type->type = lttng_ust_type_dynamic;
        event_field->type = type;
-       new_field->event_field = event_field;
+       new_field.event_field = event_field;
        /*
         * If provider is not found, we add the context anyway, but
         * it will provide a dummy context.
         */
        provider = lookup_provider_by_name(name);
        if (provider) {
-               new_field->get_size = provider->get_size;
-               new_field->record = provider->record;
-               new_field->get_value = provider->get_value;
+               new_field.get_size = provider->get_size;
+               new_field.record = provider->record;
+               new_field.get_value = provider->get_value;
        } else {
-               new_field->get_size = lttng_ust_dummy_get_size;
-               new_field->record = lttng_ust_dummy_record;
-               new_field->get_value = lttng_ust_dummy_get_value;
+               new_field.get_size = lttng_ust_dummy_get_size;
+               new_field.record = lttng_ust_dummy_record;
+               new_field.get_value = lttng_ust_dummy_get_value;
        }
+       new_field.destroy = destroy_app_ctx;
+       new_field.priv = app_ctx;
        /*
         * For application context, add it by expanding
-        * ctx array. Ownership of new_field is passed to the callee on
-        * success.
+        * ctx array.
         */
-       ret = lttng_ust_context_append_rcu(ctx, new_field);
+       ret = lttng_ust_context_append_rcu(ctx, &new_field);
        if (ret) {
-               free(type);
-               free((char *) new_field->event_field->name);
-               free(event_field);
-               free(new_field);
+               destroy_app_ctx(app_ctx);
                return ret;
        }
        return 0;
 
+error_app_ctx_alloc:
+       free(type);
 error_field_type_alloc:
-       free((char *) new_field->event_field->name);
+       free(ctx_name);
 error_field_name_alloc:
        free(event_field);
 error_event_field_alloc:
-       free(new_field);
-error_field_alloc:
        return ret;
 }

diff --git a/liblttng-ust/lttng-context.c b/liblttng-ust/lttng-context.c
index 7e558067542877f846bc7f46dee9e5e9989318c5..0aaae755cc35b324b2a77a083306acea890010cc 100644 (file)
--- a/liblttng-ust/lttng-context.c
+++ b/liblttng-ust/lttng-context.c
@@ -202,7 +202,6 @@ int lttng_ust_context_append_rcu(struct lttng_ust_ctx **ctx_p,
                free(new_ctx);
                return ret;
        }
-       /* Taking ownership of f. */
        new_ctx->fields[new_ctx->nr_fields - 1] = *f;
        lttng_context_update(new_ctx);
        lttng_ust_rcu_assign_pointer(*ctx_p, new_ctx);