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Posted to dev@qpid.apache.org by "Ken Giusti (Jira)" <ji...@apache.org> on 2021/05/07 13:05:00 UTC
[jira] [Resolved] (DISPATCH-2046) Panic in handle due to deleted
connector.
[ https://issues.apache.org/jira/browse/DISPATCH-2046?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Ken Giusti resolved DISPATCH-2046.
----------------------------------
Resolution: Fixed
> Panic in handle due to deleted connector.
> -----------------------------------------
>
> Key: DISPATCH-2046
> URL: https://issues.apache.org/jira/browse/DISPATCH-2046
> Project: Qpid Dispatch
> Issue Type: Bug
> Components: Routing Engine
> Affects Versions: 1.15.0
> Reporter: Alex Ward
> Assignee: Ken Giusti
> Priority: Blocker
> Fix For: 1.16.0
>
>
> I am seeing a segv at line 1063 due to ctx->connector being 0 in server.c:handle().
> {code:java}
> (ugdb-x86_64-7.11-261) p ctx
> $6 = (qd_connection_t *) 0x802e55890
> (ugdb-x86_64-7.11-261) p *ctx
> $7 = {prev = 0x8023df490, next = 0x802e7a890, name = 0x0, server = 0x80220d0c0, opened = false, closed = false, closed_locally = false, enqueued = 0, timer = 0x0, pn_conn = 0x8023ec050, pn_sessions = {0x0 <repeats 15 times>}, ssl = 0x0, listener = 0x0, connector = 0x0, connector_lock = 0x8023e6600, context = 0x0, user_context = 0x0, link_context = 0x0, connection_id = 12, user_id = 0x0, free_user_id = false, policy_settings = 0x0, n_sessions = 0, n_senders = 0, n_receivers = 0, open_container = 0x0, deferred_calls = {head = 0x0, tail = 0x0, scratch = 0x0, size = 0}, deferred_call_lock = 0x8023e65c0, policy_counted = false, role = 0x801a17660 "route-container", free_link_session_list = {head = 0x0, tail = 0x0, scratch = 0x0, size = 0}, strip_annotations_in = false, strip_annotations_out = false, wake = 0x8005d6e20 <connection_wake>, rhost = '\000' <repeats 1024 times>, rhost_port = '\000' <repeats 1056 times>}
> {code}
> As the comment at the start of handle() states, there is only one event being handled at a time, but it doesn’t look like there is anything to stop someone clearing ctx->connector between lines 1055 and 1063. The python code seems to be coming in and deleting the connector while handle() is using it.
> [https://github.com/apache/qpid-dispatch/blob/main/src/server.c]
> {code:java}
> 989 /* Events involving a connection or listener are serialized by the proactor so
> 990 * only one event per connection / listener will be processed at a time.
> 991 */
> 992 static bool handle(qd_server_t *qd_server, pn_event_t *e, pn_connection_t *pn_conn, qd_connection_t *ctx)
> 993 {
> 994 if (pn_conn && qdr_is_authentication_service_connection(pn_conn)) {
> 995 qdr_handle_authentication_service_connection_event(e);
> 996 return true;
> 997 }
> 998
> 999 switch (pn_event_type(e)) {
> …
> 1051 case PN_TRANSPORT_ERROR:
> 1052 {
> 1053 pn_transport_t *transport = pn_event_transport(e);
> 1054 pn_condition_t* condition = transport ? pn_transport_condition(transport) : NULL;
> 1055 if (ctx && ctx->connector) { /* Outgoing connection */
> 1056 qd_increment_conn_index(ctx);
> 1057 const qd_server_config_t *config = &ctx->connector->config;
> 1058 ctx->connector->state = CXTR_STATE_FAILED;
> 1059 char conn_msg[300];
> 1060 if (condition && pn_condition_is_set(condition)) {
> 1061 qd_format_string(conn_msg, 300, "[C%"PRIu64"] Connection to %s failed: %s %s", ctx->connection_id, config->host_port,
> 1062 pn_condition_get_name(condition), pn_condition_get_description(condition));
> 1063 strcpy(ctx->connector->conn_msg, conn_msg);
> {code}
> Another thread is at line 1063 in qd_connection_manager_delete_connector so it looks like this thread just cleared ctx->connector that is being used in handle. What is meant to be preventing this happening?
> [https://github.com/apache/qpid-dispatch/blob/main/src/connection_manager.c]
> {code:java}
> 1055 void qd_connection_manager_delete_connector(qd_dispatch_t *qd, void *impl)
> 1056 {
> 1057 qd_connector_t *ct = (qd_connector_t*) impl;
> 1058 if (ct) {
> 1059 sys_mutex_lock(ct->lock);
> 1060 if (ct->ctx) {
> 1061 ct->ctx->connector = 0;
> 1062 if(ct->ctx->pn_conn)
> 1063 qd_connection_invoke_deferred(ct->ctx, deferred_close, ct->ctx->pn_conn);
> 1064
> 1065 }
> 1066 sys_mutex_unlock(ct->lock);
> 1067 DEQ_REMOVE(qd->connection_manager->connectors, ct);
> 1068 qd_connector_decref(ct);
> 1069 }
> 1070 }
> {code}
> Does anyone have any suggestions for how to prevent this? Doesn't look like I could use ct->lock in handle().
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