[PATCH 1/2] hw/xen: Fix xen_bus_realize() error handling

[Markus Armbruster <armbru@xxxxxxxxxx>]

The Error ** argument must be NULL, &error_abort, &error_fatal, or a
pointer to a variable containing NULL.  Passing an argument of the
latter kind twice without clearing it in between is wrong: if the
first call sets an error, it no longer points to NULL for the second
call.

xen_bus_realize() is wrong that way: it passes &local_err to
xs_node_watch() in a loop.  If this fails in more than one iteration,
it can trip error_setv()'s assertion.

Fix by clearing @local_err.

Fixes: c4583c8c394e (xen-bus: reduce scope of backend watch)
Signed-off-by: Markus Armbruster <armbru@xxxxxxxxxx>
---
 hw/xen/xen-bus.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c
index 8260f1e1bb..2aacc1436f 100644
--- a/hw/xen/xen-bus.c
+++ b/hw/xen/xen-bus.c
@@ -357,6 +357,7 @@ static void xen_bus_realize(BusState *bus, Error **errp)
             error_reportf_err(local_err,
                               "failed to set up '%s' enumeration watch: ",
                               type[i]);
+            local_err = NULL;
         }
 
         g_free(node);
-- 
2.48.1