Fix: lttng-sessiond: event_context might leak

If the parsing completed but is not the expected size, the
*out_event_context object leaks.

Reported by Coverity:

    CID 1475821 (#1 of 1): Resource leak (RESOURCE_LEAK)
    Variable event_context going out of scope leaks the storage it points to.

Change-Id: I8198f7f3f1e1af3dcb377d89674402ec49cb788b
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
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 0bf8266f4f7a0912018661a4ea794c7e82d8df90..5055d59e8e1595c5451701fdc91c17a96cff7599 100644 (file)
--- a/src/bin/lttng-sessiond/client.c
+++ b/src/bin/lttng-sessiond/client.c
@@ -846,6 +846,7 @@ static enum lttng_error_code receive_lttng_event_context(
        ssize_t sock_recv_len;
        enum lttng_error_code ret_code;
        struct lttng_payload event_context_payload;
+       struct lttng_event_context *context = NULL;
 
        lttng_payload_init(&event_context_payload);
 
@@ -868,22 +869,33 @@ static enum lttng_error_code receive_lttng_event_context(
 
        /* Deserialize event. */
        {
+               ssize_t len;
                struct lttng_payload_view event_context_view =
                                lttng_payload_view_from_payload(
                                                &event_context_payload, 0, -1);
 
-               if (lttng_event_context_create_from_payload(
-                               &event_context_view, out_event_context) !=
-                               event_context_len) {
-                       ERR("Invalid event context received as part of command payload");
+               len = lttng_event_context_create_from_payload(
+                               &event_context_view, &context);
+
+               if (len < 0) {
+                       ERR("Failed to create a event context from the received buffer");
+                       ret_code = LTTNG_ERR_INVALID_PROTOCOL;
+                       goto end;
+               }
+
+               if (len != event_context_len) {
+                       ERR("Event context from the received buffer is not the advertised length: expected length = %zu, payload length = %zd", event_context_len, len);
                        ret_code = LTTNG_ERR_INVALID_PROTOCOL;
                        goto end;
                }
        }
 
+       *out_event_context = context;
+       context = NULL;
        ret_code = LTTNG_OK;
 
 end:
+       lttng_event_context_destroy(context);
        lttng_payload_reset(&event_context_payload);
        return ret_code;
 }
@@ -1361,7 +1373,7 @@ skip_domain:
        switch (cmd_ctx->lsm.cmd_type) {
        case LTTNG_ADD_CONTEXT:
        {
-               struct lttng_event_context *event_context;
+               struct lttng_event_context *event_context = NULL;
                const enum lttng_error_code ret_code =
                        receive_lttng_event_context(
                                cmd_ctx, *sock, sock_error, &event_context);