agent: Fix a race condition which results accessing finished scd.

* agent/call-daemon.c (daemon_start): Decision of connection/reuse of
CTX and assignment to ->ctx should be done with the lock.

--

When scdaemon is exiting and agent tries to spawn/connect/reconnect,
there is a race condition between detecting finish of scd and
spawn/connect/reconnect.

Signed-off-by: NIIBE Yutaka <[email protected]>
(cherry picked from commit 563bfbb0be4ebbc85bc56426541f666839e6aa13)

1 files changed, 6 insertions, 4 deletions

diff --git a/agent/call-daemon.c b/agent/call-daemon.c
index e1c5669e9..f200af28f 100644
--- a/agent/call-daemon.c
+++ b/agent/call-daemon.c
@@ -511,13 +511,12 @@ daemon_start (enum daemon_type type, ctrl_t ctrl)
   }
 
  leave:
-  rc = npth_mutex_unlock (&start_daemon_lock);
-  if (rc)
-    log_error ("failed to release the start_daemon lock: %s\n", strerror (rc));
-
   xfree (abs_homedir);
   if (err)
     {
+      rc = npth_mutex_unlock (&start_daemon_lock);
+      if (rc)
+        log_error ("failed to release the start_daemon lock: %s\n", strerror (rc));
       daemon_unlock (type, ctrl, err);
       if (ctx)
 	assuan_release (ctx);
@@ -526,6 +525,9 @@ daemon_start (enum daemon_type type, ctrl_t ctrl)
     {
       ctrl->d_local[type]->ctx = ctx;
       ctrl->d_local[type]->invalid = 0;
+      rc = npth_mutex_unlock (&start_daemon_lock);
+      if (rc)
+        log_error ("failed to release the start_daemon lock: %s\n", strerror (rc));
     }
   return err;
 }