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 b5c305a951cc23e6a290401ce2b5c03b894e1d3c..77bb90db02d24d42ccdf6c996a3d1c82e9266e70 100644 (file)
--- a/liblttng-ust/lttng-ust-abi.c
+++ b/liblttng-ust/lttng-ust-abi.c
@@ -1107,6 +1107,9 @@ 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 ead0d7fecbc6d15f03ab120ff9f3524b063bf454..708b9192f22b62b14985f8d7ffa3c7d423813d2d 100644 (file)
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -1080,6 +1080,8 @@ 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,
@@ -1095,6 +1097,22 @@ 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: