From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Tue, 15 Dec 2020 14:01:38 +0000 (-0500)
Subject: Fix: stream fd leaks on error
X-Git-Url: http://git.efficios.com/?p=deliverable%2Flttng-ust.git;a=commitdiff_plain;h=c1200628ceef3b1764cb89a52b3092799f434f1f

Fix: stream fd leaks on error

Use a regular pattern for all commands:

If the command callback takes ownership of a pointer or file descriptor,
it sets them to NULL or -1. Therefore, the caller can always try to free
the pointer, or close it if it is greater or equal to 0.

This eliminates memory and fd leaks on error.

Change-Id: I447129ab1672ce4fc6cf3c0baf18dbf27bfcfaf8
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/liblttng-ust/lttng-ust-abi.c b/liblttng-ust/lttng-ust-abi.c
index daf0d5e4..1bf7a5ae 100644
--- a/liblttng-ust/lttng-ust-abi.c
+++ b/liblttng-ust/lttng-ust-abi.c
@@ -772,6 +772,9 @@ int lttng_abi_map_stream(int channel_objd, struct lttng_ust_stream *info,
 		info->stream_nr, info->len);
 	if (ret)
 		goto error_add_stream;
+	/* Take ownership of shm_fd and wakeup_fd. */
+	uargs->stream.shm_fd = -1;
+	uargs->stream.wakeup_fd = -1;
 
 	return 0;
 
diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index 3d60596a..2bed9be1 100644
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -958,6 +958,8 @@ int handle_message(struct sock_info *sock_info,
 	}
 	case LTTNG_UST_STREAM:
 	{
+		int close_ret;
+
 		/* Receive shm_fd, wakeup_fd */
 		ret = ustcomm_recv_stream_from_sessiond(sock,
 			NULL,
@@ -973,6 +975,22 @@ int handle_message(struct sock_info *sock_info,
 					&args, sock_info);
 		else
 			ret = -ENOSYS;
+		if (args.stream.shm_fd >= 0) {
+			lttng_ust_lock_fd_tracker();
+			close_ret = close(args.stream.shm_fd);
+			lttng_ust_unlock_fd_tracker();
+			args.stream.shm_fd = -1;
+			if (close_ret)
+				PERROR("close");
+		}
+		if (args.stream.wakeup_fd >= 0) {
+			lttng_ust_lock_fd_tracker();
+			close_ret = close(args.stream.wakeup_fd);
+			lttng_ust_unlock_fd_tracker();
+			args.stream.wakeup_fd = -1;
+			if (close_ret)
+				PERROR("close");
+		}
 		break;
 	}
 	case LTTNG_UST_CONTEXT: