From: Keir Fraser <keir@xen.org>
To: Jan Beulich <JBeulich@suse.com>, Matthew Daley <mattjd@gmail.com>
Cc: xen-devel@lists.xen.org
Subject: Re: [PATCH] xen: Fix xenctl_cpumap_to_cpumask buffer size check
Date: Tue, 13 Nov 2012 10:10:31 +0000 [thread overview]
Message-ID: <CCC7CD17.5206A%keir@xen.org> (raw)
In-Reply-To: <50A214B902000078000A7F88@nat28.tlf.novell.com>
On 13/11/2012 08:36, "Jan Beulich" <JBeulich@suse.com> wrote:
>> Fix by using the correct cpumask buffer size in place of sizeof.
>>
>> Signed-off-by: Matthew Daley <mattjd@gmail.com>
>
> Acked-by: Jan Beulich <jbeulich@suse.com>
>
> However, I would have preferred the adjustment to be ...
>
>> diff --git a/xen/common/domctl.c b/xen/common/domctl.c
>> index e153cb4..204e951 100644
>> --- a/xen/common/domctl.c
>> +++ b/xen/common/domctl.c
>> @@ -78,7 +78,7 @@ int xenctl_cpumap_to_cpumask(
>> {
>> if ( copy_from_guest(bytemap, xenctl_cpumap->bitmap, copy_bytes) )
>> err = -EFAULT;
>> - if ( (xenctl_cpumap->nr_cpus & 7) && (guest_bytes <=
>> sizeof(bytemap)) )
>> + if ( (xenctl_cpumap->nr_cpus & 7) && (guest_bytes <= (nr_cpu_ids +
>> 7) / 8) )
>
> if ( (xenctl_cpumap->nr_cpus & 7) && (guest_bytes <= copy_bytes) )
>
> or even (considering that guest_bytes >= copy_bytes due to the
> way copy_bytes gets initialized)
>
> if ( (xenctl_cpumap->nr_cpus & 7) && (guest_bytes == copy_bytes) )
>
> to make explicit when exactly the masking is necessary.
Any of the three alternatives is fine by me.
Acked-by: Keir Fraser <keir@xen.org>
next prev parent reply other threads:[~2012-11-13 10:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-13 6:04 [PATCH] xen: Fix xenctl_cpumap_to_cpumask buffer size check Matthew Daley
2012-11-13 8:36 ` Jan Beulich
2012-11-13 10:10 ` Keir Fraser [this message]
2012-11-13 10:17 ` Matthew Daley
2012-11-13 10:58 ` Keir Fraser
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