From d147c5c868813a4d2e42777b574f7a2c94e3a092 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Tue, 15 Dec 2020 08:48:59 -0500 Subject: [PATCH] Fix: channel leak 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: I0f9cba5fc0f4c095c8ec8f3e8970de8a10386876 Signed-off-by: Mathieu Desnoyers --- liblttng-ust/lttng-ust-abi.c | 19 ++++--------------- liblttng-ust/lttng-ust-comm.c | 11 +++++++++++ 2 files changed, 15 insertions(+), 15 deletions(-) diff --git a/liblttng-ust/lttng-ust-abi.c b/liblttng-ust/lttng-ust-abi.c index 2de4df1a..daf0d5e4 100644 --- a/liblttng-ust/lttng-ust-abi.c +++ b/liblttng-ust/lttng-ust-abi.c @@ -438,6 +438,10 @@ int lttng_abi_map_channel(int session_objd, goto handle_error; } + /* Ownership of chan_data and wakeup_fd taken by channel handle. */ + uargs->channel.chan_data = NULL; + uargs->channel.wakeup_fd = -1; + chan = shmp(channel_handle, channel_handle->chan); assert(chan); chan->handle = channel_handle; @@ -521,24 +525,9 @@ alloc_error: channel_destroy(chan, channel_handle, 0); return ret; - /* - * error path before channel creation (owning chan_data and - * wakeup_fd). - */ handle_error: active: invalid: - { - int close_ret; - - lttng_ust_lock_fd_tracker(); - close_ret = close(wakeup_fd); - lttng_ust_unlock_fd_tracker(); - if (close_ret) { - PERROR("close"); - } - } - free(chan_data); return ret; } diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c index e449edad..18063ffe 100644 --- a/liblttng-ust/lttng-ust-comm.c +++ b/liblttng-ust/lttng-ust-comm.c @@ -923,6 +923,17 @@ int handle_message(struct sock_info *sock_info, &args, sock_info); else ret = -ENOSYS; + if (args.channel.wakeup_fd >= 0) { + int close_ret; + + lttng_ust_lock_fd_tracker(); + close_ret = close(args.channel.wakeup_fd); + lttng_ust_unlock_fd_tracker(); + args.channel.wakeup_fd = -1; + if (close_ret) + PERROR("close"); + } + free(args.channel.chan_data); break; } case LTTNG_UST_STREAM: -- 2.34.1