Re: [Xen-devel] [PATCH 4/6] sysctl: use xmalloc_array() for XEN_SYSCTL_page_offline_op

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 05/02/2020 13:16, Jan Beulich wrote:
> This is more robust than the raw xmalloc_bytes().
>
> Also add a sanity check on the input page range.
It feels to me that the commit message/title should focus on the sanity 
check. The xmalloc_array() is just a cleanup is "less important".
Argually the clean-up should be in a separate patch but I can appreciate 
they are somewhat related.
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> --- a/xen/common/sysctl.c
> +++ b/xen/common/sysctl.c
> @@ -187,13 +187,17 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xe
>           uint32_t *status, *ptr;
>           mfn_t mfn;
>   
> +        ret = -EINVAL;
> +        if ( op->u.page_offline.end < op->u.page_offline.start )
> +            break;
> +
>           ret = xsm_page_offline(XSM_HOOK, op->u.page_offline.cmd);
>           if ( ret )
>               break;
>   
> -        ptr = status = xmalloc_bytes( sizeof(uint32_t) *
> -                                (op->u.page_offline.end -
> -                                  op->u.page_offline.start + 1));
> +        ptr = status = xmalloc_array(uint32_t,
> +                                     (op->u.page_offline.end -
> +                                      op->u.page_offline.start + 1));
>           if ( !status )
>           {
>               dprintk(XENLOG_WARNING, "Out of memory for page offline op\n");
--
Julien Grall

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