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Re: [Qemu-devel] [PATCH v2] hostmem: fix crash when querying empty host-
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v2] hostmem: fix crash when querying empty host-nodes property via QMP |
Date: |
Thu, 14 Feb 2019 09:52:54 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 |
On 2/14/19 4:57 AM, Igor Mammedov wrote:
> 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 not set hostmem's "host-nodes"
> property, HostMemoryBackend::host_nodes bitmap doesn't have
> any bits set in it, which leads to find_first_bit() returning
> MAX_NODES and consequently to an early return from
> host_memory_backend_get_host_nodes() without calling visitor.
>
> Fix it by calling visitor even if "host-nodes" property wasn't
> set before exiting from property getter to return valid empty
> list.
>
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
> v2:
> * fixup commit message to put emphasis on property instead
> local variable host_nodes and make explanation more hopefully
> more clear. (Markus Armbruster <address@hidden>)
> ---
> backends/hostmem.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
Reviewed-by: Eric Blake <address@hidden>
> diff --git a/backends/hostmem.c b/backends/hostmem.c
> index 87b19d2111..04baf479a1 100644
> --- a/backends/hostmem.c
> +++ b/backends/hostmem.c
> @@ -88,7 +88,7 @@ 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));
> @@ -106,6 +106,7 @@ 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);
> }
>
>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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