From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Mon, 7 Oct 2019 22:26:51 +0000 (-0400)
Subject: Fix: sessiond: client socket not created by the main thread
X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=commitdiff_plain;h=0f68efb616cd046543e5fc5a091466ec26df2216

Fix: sessiond: client socket not created by the main thread

The client socket is not created by the session daemon's main thread
which causes calls to umask() to be issued from multiple threads.

Since umask manipulates a process-wide ressource, it should be only be
used by a single thread.

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

diff --git a/src/bin/lttng-sessiond/client.c b/src/bin/lttng-sessiond/client.c
index 870277534..327c1fe17 100644
--- a/src/bin/lttng-sessiond/client.c
+++ b/src/bin/lttng-sessiond/client.c
@@ -44,6 +44,7 @@ static bool is_root;
 static struct thread_state {
 	sem_t ready;
 	bool running;
+	int client_sock;
 } thread_state;
 
 static void set_thread_status(bool running)
@@ -2022,7 +2023,7 @@ static void *thread_manage_clients(void *data)
 	uint32_t revents, nb_fd;
 	struct command_ctx *cmd_ctx = NULL;
 	struct lttng_poll_event events;
-	int client_sock = -1;
+	const int client_sock = thread_state.client_sock;
 	struct lttng_pipe *quit_pipe = data;
 	const int thread_quit_pipe_fd = lttng_pipe_get_readfd(quit_pipe);
 
@@ -2031,10 +2032,6 @@ static void *thread_manage_clients(void *data)
 	is_root = (getuid() == 0);
 
 	pthread_cleanup_push(thread_init_cleanup, NULL);
-	client_sock = create_client_sock();
-	if (client_sock < 0) {
-		goto error_listen;
-	}
 
 	rcu_register_thread();
 
@@ -2273,11 +2270,9 @@ error:
 error_listen:
 error_create_poll:
 	unlink(config.client_unix_sock_path.value);
-	if (client_sock >= 0) {
-		ret = close(client_sock);
-		if (ret) {
-			PERROR("close");
-		}
+	ret = close(client_sock);
+	if (ret) {
+		PERROR("close");
 	}
 
 	if (err) {
@@ -2306,7 +2301,8 @@ struct lttng_thread *launch_client_thread(void)
 {
 	bool thread_running;
 	struct lttng_pipe *client_quit_pipe;
-	struct lttng_thread *thread;
+	struct lttng_thread *thread = NULL;
+	int client_sock_fd = -1;
 
 	sem_init(&thread_state.ready, 0, 0);
 	client_quit_pipe = lttng_pipe_open(FD_CLOEXEC);
@@ -2314,6 +2310,12 @@ struct lttng_thread *launch_client_thread(void)
 		goto error;
 	}
 
+	client_sock_fd = create_client_sock();
+	if (client_sock_fd < 0) {
+		goto error;
+	}
+
+	thread_state.client_sock = client_sock_fd;
 	thread = lttng_thread_create("Client management",
 			thread_manage_clients,
 			shutdown_client_thread,
@@ -2322,6 +2324,9 @@ struct lttng_thread *launch_client_thread(void)
 	if (!thread) {
 		goto error;
 	}
+	/* The client thread now owns the client sock fd and the quit pipe. */
+	client_sock_fd = -1;
+	client_quit_pipe = NULL;
 
 	/*
 	 * This thread is part of the threads that need to be fully
@@ -2329,11 +2334,16 @@ struct lttng_thread *launch_client_thread(void)
 	 */
 	thread_running = wait_thread_status();
 	if (!thread_running) {
-		lttng_thread_put(thread);
-		thread = NULL;
+		goto error;
 	}
 	return thread;
 error:
+	if (client_sock_fd >= 0) {
+		if (close(client_sock_fd)) {
+			PERROR("Failed to close client socket");
+		}
+	}
+	lttng_thread_put(thread);
 	cleanup_client_thread(client_quit_pipe);
 	return NULL;
 }
diff --git a/src/bin/lttng-sessiond/thread.c b/src/bin/lttng-sessiond/thread.c
index c685442ba..ff6c0962f 100644
--- a/src/bin/lttng-sessiond/thread.c
+++ b/src/bin/lttng-sessiond/thread.c
@@ -140,6 +140,9 @@ bool lttng_thread_get(struct lttng_thread *thread)
 
 void lttng_thread_put(struct lttng_thread *thread)
 {
+	if (!thread) {
+		return;
+	}
 	assert(thread->ref.refcount);
 	urcu_ref_put(&thread->ref, lttng_thread_release);
 }