From 0f68efb616cd046543e5fc5a091466ec26df2216 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Mon, 7 Oct 2019 18:26:51 -0400
Subject: [PATCH] Fix: sessiond: client socket not created by the main thread
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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>
---
 src/bin/lttng-sessiond/client.c | 36 +++++++++++++++++++++------------
 src/bin/lttng-sessiond/thread.c |  3 +++
 2 files changed, 26 insertions(+), 13 deletions(-)

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);
 }
-- 
2.34.1