From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:54814) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1guEu1-00051e-Ci for qemu-devel@nongnu.org; Thu, 14 Feb 2019 06:10:02 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1guEgf-0002el-Us for qemu-devel@nongnu.org; Thu, 14 Feb 2019 05:56:16 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42334) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1guEgc-0002X6-1L for qemu-devel@nongnu.org; Thu, 14 Feb 2019 05:56:13 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 028C189AD7 for ; Thu, 14 Feb 2019 10:56:06 +0000 (UTC) Date: Thu, 14 Feb 2019 11:56:03 +0100 From: Igor Mammedov Message-ID: <20190214115603.1ca98b68@redhat.com> In-Reply-To: <877ee36cj4.fsf@dusky.pond.sub.org> References: <1549377087-205549-1-git-send-email-imammedo@redhat.com> <877ee36cj4.fsf@dusky.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] hostmem: fix crash when querying empty host-nodes property via QMP List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: qemu-devel@nongnu.org, ehabkost@redhat.com On Wed, 13 Feb 2019 14:30:55 +0100 Markus Armbruster wrote: > Igor Mammedov writes: > > > QEMU will crashes with > > qapi/qobject-output-visitor.c:210: qobject_output_complete: Assertion `qov->root && ((&qov->stack)->slh_first == ((void *)0))' failed > > when trying to get value of empty hostmem.host-nodes property. > > > > Fix it by calling visitor even if host-nodes wasn't set > > before exiting from property getter to return empty list. > > host-nodes or host_nodes? > > If local variable host_nodes: that one's always set. The case you fix > has it set to NULL. it's about property host-nodes: value = find_first_bit(backend->host_nodes, MAX_NODES); if (value == MAX_NODES) { goto ret; } when no bits set, it exits without visiting being returned list. I'll send v2 with commit message giving more explanation to make it clearer. > > Signed-off-by: Igor Mammedov > > --- > > backends/hostmem.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/backends/hostmem.c b/backends/hostmem.c > > index 0c8ef17..fe14be5 100644 > > --- a/backends/hostmem.c > > +++ b/backends/hostmem.c > > @@ -86,7 +86,7 @@ host_memory_backend_get_host_nodes(Object *obj, Visitor *v, const char *name, > > > > value = find_first_bit(backend->host_nodes, MAX_NODES); > > if (value == MAX_NODES) { > > - return; > > + goto ret; > > } > > > > *node = g_malloc0(sizeof(**node)); > > @@ -104,6 +104,7 @@ host_memory_backend_get_host_nodes(Object *obj, Visitor *v, const char *name, > > node = &(*node)->next; > > } while (true); > > > > +ret: > > visit_type_uint16List(v, name, &host_nodes, errp); > > } > > Yes, an empty list needs to be visited just like a non-empty list. > > Patch looks good. >