Re: [PATCH 12/12] xen/cpupool: make per-cpupool sched-gran hypfs node writable

[Jan Beulich <jbeulich@xxxxxxxx>]

On 26.10.2020 10:13, Juergen Gross wrote:
> @@ -1088,13 +1098,58 @@ static int cpupool_gran_read(const struct hypfs_entry 
> *entry,
>      return copy_to_guest(uaddr, name, strlen(name) + 1) ? -EFAULT : 0;
>  }
>  
> +static int cpupool_gran_write(struct hypfs_entry_leaf *leaf,
> +                              XEN_GUEST_HANDLE_PARAM(void) uaddr,
> +                              unsigned int ulen)
> +{
> +    const struct hypfs_dyndir_id *data;
> +    struct cpupool *cpupool;
> +    enum sched_gran gran;
> +    unsigned int sched_gran;
> +    char name[SCHED_GRAN_NAME_LEN];
> +    int ret = 0;
> +
> +    if ( ulen > SCHED_GRAN_NAME_LEN )
> +        return -ENOSPC;
> +
> +    if ( copy_from_guest(name, uaddr, ulen) )
> +        return -EFAULT;
> +
> +    sched_gran = sched_gran_get(name, &gran) ? 0
> +                                             : 
> cpupool_check_granularity(gran);
> +    if ( memchr(name, 0, ulen) != (name + ulen - 1) || sched_gran == 0 )
> +        return -EINVAL;

I guess the memchr() check wants to happen before the call to
sched_gran_get()?

Jan