Re: [Xen-devel] [PATCH] xen/public: Correct the definition of GNTTAB_CACHE_SOURCE_GREF

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Andrew,

On 17/10/17 15:11, Andrew Cooper wrote:
> Discovered when running the XSA-232 PoC on a UBSAN-enabled hypervisor.
>
>    (d79) XSA-232 PoC
>    (XEN) 
> ================================================================================
>    (XEN) UBSAN: Undefined behaviour in grant_table.c:3217:25
>    (XEN) left shift of 1 by 31 places cannot be represented in type 'int'
>    (XEN) ----[ Xen-4.10.0-rc  x86_64  debug=y   Tainted:    H ]----
>
> Update all of the GNTTAB_CACHE_* constants to be unsigned integers.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Release-acked-by: Julien Grall <julien.grall@xxxxxxxxxx>

Cheers,

> ---
> CC: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Tim Deegan <tim@xxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
>
> This is a trivial bugfix, and is low risk for 4.10
> ---
>   xen/include/public/grant_table.h | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/xen/include/public/grant_table.h b/xen/include/public/grant_table.h
> index 018036e..180d62c 100644
> --- a/xen/include/public/grant_table.h
> +++ b/xen/include/public/grant_table.h
> @@ -589,9 +589,9 @@ struct gnttab_cache_flush {
>       } a;
>       uint16_t offset; /* offset from start of grant */
>       uint16_t length; /* size within the grant */
> -#define GNTTAB_CACHE_CLEAN          (1<<0)
> -#define GNTTAB_CACHE_INVAL          (1<<1)
> -#define GNTTAB_CACHE_SOURCE_GREF    (1<<31)
> +#define GNTTAB_CACHE_CLEAN          (1u<<0)
> +#define GNTTAB_CACHE_INVAL          (1u<<1)
> +#define GNTTAB_CACHE_SOURCE_GREF    (1u<<31)
>       uint32_t op;
>   };
>   typedef struct gnttab_cache_flush gnttab_cache_flush_t;
--
Julien Grall

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