Re: [Xen-devel] [PATCH] libxc: fix out of range shift in populate_acpi_pages

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 09/28/2016 11:02 AM, Wei Liu wrote:
> "unsigned int" is only 4-byte long and "4" is treated as int. The shift
> would overflow.  Use "unsigned long" (to match the type of idx) and
> "4UL" instead.
>
> Caught by clang compilation test.
>
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>

> ---
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> ---
>  tools/libxc/xc_dom_core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/libxc/xc_dom_core.c b/tools/libxc/xc_dom_core.c
> index 87b450c..b3feb42 100644
> --- a/tools/libxc/xc_dom_core.c
> +++ b/tools/libxc/xc_dom_core.c
> @@ -1048,7 +1048,7 @@ static int populate_acpi_pages(struct xc_dom_image *dom,
>      xc_interface *xch = dom->xch;
>      uint32_t domid = dom->guest_domid;
>      unsigned long idx;
> -    unsigned int first_high_idx = (4 << 30) >> PAGE_SHIFT; /* 4GB */
> +    unsigned long first_high_idx = (4UL << 30) >> PAGE_SHIFT; /* 4GB */
>  
>      for ( ; num_pages; num_pages--, extents++ )
>      {


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