Fix double free and out of order delete session

[lttng-tools.git] / lttng-sessiond / ust-app.c

diff --git a/lttng-sessiond/ust-app.c b/lttng-sessiond/ust-app.c
index a9c1c764c0359ca3a81dbb22aa088c093e456eda..5976270604cd0ffd9e271a38c669bbbe8f956c6f 100644 (file)
--- a/lttng-sessiond/ust-app.c
+++ b/lttng-sessiond/ust-app.c
@@ -1177,8 +1177,15 @@ static int create_ust_app_metadata(struct ust_app_session *ua_sess,
 
                ret = open_ust_metadata(app, ua_sess);
                if (ret < 0) {
+                       DBG3("Opening metadata failed. Cleaning up memory");
+
                        /* Cleanup failed metadata struct */
                        free(ua_sess->metadata);
+                       /*
+                        * This is very important because delete_ust_app_session check if
+                        * the pointer is null or not in order to delete the metadata.
+                        */
+                       ua_sess->metadata = NULL;
                        goto error;
                }
 
@@ -1958,6 +1965,11 @@ int ust_app_stop_trace(struct ltt_ust_session *usess, struct ust_app *app)
                goto error_rcu_unlock;
        }
 
+       /* Not started, continuing. */
+       if (ua_sess->started == 0) {
+               goto end;
+       }
+
        /* This inhibits UST tracing */
        ret = ustctl_stop_session(app->key.sock, ua_sess->handle);
        if (ret < 0) {
@@ -1973,9 +1985,8 @@ int ust_app_stop_trace(struct ltt_ust_session *usess, struct ust_app *app)
                        node.node) {
                ret = ustctl_sock_flush_buffer(app->key.sock, ua_chan->obj);
                if (ret < 0) {
-                       ERR("UST app PID %d channel %s flush failed",
-                                       app->key.pid, ua_chan->name);
-                       ERR("Ended with ret %d", ret);
+                       ERR("UST app PID %d channel %s flush failed with ret %d",
+                                       app->key.pid, ua_chan->name, ret);
                        /* Continuing flushing all buffers */
                        continue;
                }
@@ -1984,12 +1995,14 @@ int ust_app_stop_trace(struct ltt_ust_session *usess, struct ust_app *app)
        /* Flush all buffers before stopping */
        ret = ustctl_sock_flush_buffer(app->key.sock, ua_sess->metadata->obj);
        if (ret < 0) {
-               ERR("UST app PID %d metadata flush failed", app->key.pid);
-               ERR("Ended with ret %d", ret);
+               ERR("UST app PID %d metadata flush failed with ret %d", app->key.pid,
+                               ret);
        }
 
-       rcu_read_unlock();
+       ua_sess->started = 0;
 
+end:
+       rcu_read_unlock();
        return 0;
 
 error_rcu_unlock:
@@ -2021,13 +2034,14 @@ int ust_app_destroy_trace(struct ltt_ust_session *usess, struct ust_app *app)
        ua_sess = caa_container_of(node, struct ust_app_session, node);
        ret = lttng_ht_del(app->sessions, &iter);
        assert(!ret);
-       delete_ust_app_session(app->key.sock, ua_sess);
        obj.handle = ua_sess->handle;
        obj.shm_fd = -1;
        obj.wait_fd = -1;
        obj.memory_map_size = 0;
        ustctl_release_object(app->key.sock, &obj);
 
+       delete_ust_app_session(app->key.sock, ua_sess);
+
        rcu_read_unlock();
 
        /* Quiescent wait after stopping trace */