discover/event: Ensure event struct exists for async callers

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>

1 files changed, 2 insertions, 0 deletions

diff --git a/discover/device-handler.c b/discover/device-handler.c
index f6b6d22..346cb02 100644
--- a/discover/device-handler.c
+++ b/discover/device-handler.c
@@ -900,6 +900,7 @@ int device_handler_dhcp(struct device_handler *handler,
 
 	/* create our context */
 	ctx = device_handler_discover_context_create(handler, dev);
+	talloc_steal(ctx, event);
 	ctx->event = event;
 
 	iterate_parsers(ctx);
@@ -1171,6 +1172,7 @@ void device_handler_process_url(struct device_handler *handler,
 	if (pb_url->scheme == pb_url_file)
 		dev->device->type = DEVICE_TYPE_ANY;
 	ctx = device_handler_discover_context_create(handler, dev);
+	talloc_steal(ctx, event);
 	ctx->event = event;
 
 	iterate_parsers(ctx);