Allocate PAM DP request data on responder context

https://fedorahosted.org/sssd/ticket/1869

Currently the private data passed to the PAM request is a structure
allocated on the client context. But in the odd case where the back end
would be stopped or stuck until the idle timeout hits, the DP callback
would access data that were freed when the client timed out.

This patch introduces a new structure allocated on responder context,
whose only purpose is to live as long as the request is active.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/responder/pam/pamsrv_cmd.c b/src/responder/pam/pamsrv_cmd.c
index e6300a759..ba4e969ff 100644
--- a/src/responder/pam/pamsrv_cmd.c
+++ b/src/responder/pam/pamsrv_cmd.c
@@ -739,6 +739,17 @@ done:
     return ret;
 }
 
+static int pam_auth_req_destructor(struct pam_auth_req *preq)
+{
+    if (preq && preq->dpreq_spy) {
+        /* If there is still a request pending, tell the spy
+         * the client is going away
+         */
+        preq->dpreq_spy->preq = NULL;
+    }
+    return 0;
+}
+
 static int pam_forwarder(struct cli_ctx *cctx, int pam_cmd)
 {
     struct sss_domain_info *dom;
@@ -754,6 +765,7 @@ static int pam_forwarder(struct cli_ctx *cctx, int pam_cmd)
     if (!preq) {
         return ENOMEM;
     }
+    talloc_set_destructor(preq, pam_auth_req_destructor);
     preq->cctx = cctx;
 
     preq->pd = create_pam_data(preq);