Re: [Xen-devel] [PATCH 3/4] hvm/dmop: Implement copy_{to, from}_guest_buf_offset() helpers

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.04.17 at 19:59, <jennifer.herbert@xxxxxxxxxx> wrote:
> @@ -44,15 +45,20 @@ static bool _raw_copy_from_guest_buf(void *dst,
>  
>      buf_bytes =  args->buf[buf_idx].size;
>  
> -    if ( dst_bytes > buf_bytes )
> +    if ( offset_bytes >= buf_bytes ||
> +         (offset_bytes + dst_bytes) < offset_bytes ||
> +         (offset_bytes + dst_bytes) > buf_bytes )
>          return false;

Looks like the first of these checks is redundant with the third
one, especially since - afaics - we don't even need to consider
the special case of dst_bytes being zero (and if we still wanted
to, this could be folded into the second check by making it <=
instead of < ).

Other than that
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Jan


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