discover/event: Ensure event struct exists for async callersv1.2.4

When handling an event, user_event_handle_message() creates an event
struct with relevant parameters. Once user_event_handle_message() is
finished it frees the struct.
However in the case of a dhcp or add_url event, asynchronous jobs may be
spawned that will later reference the event struct. In particular this
becomes a problem when pxe_process_pair() handles an IPAPPEND name/value
pair and tries to access event->device.

In the case of dhcp and add_url events, we avoid this by changing the
event struct's talloc parent to the discover_context struct which
persists until all async pxe jobs have completed.

Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
(cherry picked from commit a50d5fe279db71cf85fabeb675c99b167ec63dcb)

1 files changed, 5 insertions, 3 deletions

diff --git a/discover/user-event.c b/discover/user-event.c
index 7350b6c..d9f5bd4 100644
--- a/discover/user-event.c
+++ b/discover/user-event.c
@@ -503,13 +503,13 @@ static void user_event_handle_message(struct user_event *uev, char *buf,
 		break;
 	case EVENT_ACTION_URL:
 		result = user_event_url(uev, event);
-		break;
+		goto out;
 	case EVENT_ACTION_CONF:
 		result = user_event_conf(uev, event);
 		break;
 	case EVENT_ACTION_DHCP:
 		result = user_event_dhcp(uev, event);
-		break;
+		goto out;
 	case EVENT_ACTION_BOOT:
 		result = user_event_boot(uev, event);
 		break;
@@ -520,8 +520,10 @@ static void user_event_handle_message(struct user_event *uev, char *buf,
 		break;
 	}
 
+	/* user_event_url() and user_event_dhcp() will steal the event context,
+	 * but all others still need to free */
 	talloc_free(event);
-
+out:
 	return;
 }