FO: Check server validity before setting status

The list of resolved servers is allocated on the back end context and
kept in the fo_service structure. However, a single request often
resolves a server and keeps a pointer until the end of a request and
only then gives feedback about the server based on the request result.

This presents a big race condition in case the SRV resolution is used.
When there are requests coming in in parallel, it is possible that an
incoming request will invalidate a server until another request that
holds a pointer to the original server is able to give a feedback.

This patch simply checks if a server is in the list of servers
maintained by a service before reading its status.

https://fedorahosted.org/sssd/ticket/1364

1 files changed, 1 insertions, 0 deletions

diff --git a/src/providers/dp_backend.h b/src/providers/dp_backend.h
index b98d15078..357d58910 100644
--- a/src/providers/dp_backend.h
+++ b/src/providers/dp_backend.h
@@ -242,6 +242,7 @@ struct tevent_req *be_resolve_server_send(TALLOC_CTX *memctx,
 int be_resolve_server_recv(struct tevent_req *req, struct fo_server **srv);
 
 void be_fo_set_port_status(struct be_ctx *ctx,
+                           const char *service_name,
                            struct fo_server *server,
                            enum port_status status);