From: Markus Armbruster <armbru@redhat.com>
Date: Fri, 14 Mar 2025 14:34:59 +0000 (+0100)
Subject: hw/xen: Fix xen_bus_realize() error handling
X-Git-Tag: v10.0.0-rc1~3^2~5
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=de7b18083bfed4e1a01bb40b4ad050c47d2011fa;p=thirdparty%2Fqemu.git

hw/xen: Fix xen_bus_realize() error handling

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@redhat.com>
Message-ID: <20250314143500.2449658-2-armbru@redhat.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
---

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);