[libvirt] [PATCH] qemu: Avoid memleak on failure to format blockjobs

[Eric Blake]

On 10/18/18 3:08 PM, Eric Blake wrote:
> virXMLFormatElement() frees attrBuf on success, but not necessarily
> on failure. Most other callers of this function take the time to
> reset attrBuf afterwords, but qemuDomainObjPrivateXMLFOrmatBlockjobs()
> was relying on it succeeding, and could thus result in a memory leak.
> 
> Signed-off-by: Eric Blake <eblake at redhat.com>
> ---
>   src/qemu/qemu_domain.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> index dd67be5e2a..ad7a6fe136 100644
> --- a/src/qemu/qemu_domain.c
> +++ b/src/qemu/qemu_domain.c
> @@ -2232,11 +2232,15 @@ qemuDomainObjPrivateXMLFormatBlockjobs(virBufferPtr buf,
>   {
>       virBuffer attrBuf = VIR_BUFFER_INITIALIZER;
>       bool bj = qemuDomainHasBlockjob(vm, false);
> +    ret = -1;

I need to quit editing patches in my mailer. As written, this obviously 
doesn't compile; s/ret/int ret/

> 
>       virBufferAsprintf(&attrBuf, " active='%s'",
>                         virTristateBoolTypeToString(virTristateBoolFromBool(bj)));
> 
> -    return virXMLFormatElement(buf, "blockjobs", &attrBuf, NULL);
> +    ret = virXMLFormatElement(buf, "blockjobs", &attrBuf, NULL);
> + cleanup:

and this label is unused.

> +    virBufferFreeAndReset(&attrBuf);
> +    return ret;
>   }
> 
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org