Re: [PATCH v5 1/9] hvm_set_ioreq_page() releases wrong page in error path

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 01/05/14 13:08, Paul Durrant wrote:
> The function calls prepare_ring_for_helper() to acquire a mapping for the
> given gmfn, then checks (under lock) to see if the ioreq page is already
> set up but, if it is, the function then releases the in-use ioreq page
> mapping on the error path rather than the one it just acquired. This patch
> fixes this bug.
>
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> Cc: Keir Fraser <keir@xen.org>
> Cc: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

> ---
>  xen/arch/x86/hvm/hvm.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index ac05160..3dec1eb 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -496,7 +496,7 @@ static int hvm_set_ioreq_page(
>  
>      if ( (iorp->va != NULL) || d->is_dying )
>      {
> -        destroy_ring_for_helper(&iorp->va, iorp->page);
> +        destroy_ring_for_helper(&va, page);
>          spin_unlock(&iorp->lock);
>          return -EINVAL;
>      }