On 07/03/2019 10:31, Jan Beulich wrote:
> e820.c: In function ‘clip_to_limit’:
> .../xen/include/asm/string.h:10:26: error: ‘__builtin_memmove’ offset [-16, 
> -36] is out of the bounds [0, 20484] of
> object ‘e820’ with type ‘struct e820map’ [-Werror=array-bounds]
>    10 | #define memmove(d, s, n) __builtin_memmove(d, s, n)
>       |                          ^~~~~~~~~~~~~~~~~~~~~~~~~~
> e820.c:404:13: note: in expansion of macro ‘memmove’
>   404 |             memmove(&e820.map[i], &e820.map[i+1],
>       |             ^~~~~~~
> e820.c:36:16: note: ‘e820’ declared here
>    36 | struct e820map e820;
>       |                ^~~~
>
> While I can't see where the negative offsets would come from, converting
> the loop index to unsigned type helps. Take the opportunity and also
> convert several other local variables and copy_e820_map()'s second
> parameter to unsigned int (and bool in one case).
>
> Reported-by: Charles Arnold <carn...@suse.com>
> Signed-off-by: Jan Beulich <jbeul...@suse.com>

Acked-by: Andrew Cooper <andrew.coop...@citrix.com>, with one request.

>
> --- a/xen/arch/x86/e820.c
> +++ b/xen/arch/x86/e820.c
> @@ -304,7 +300,7 @@ int __init sanitize_e820_map(struct e820
>   * thinkpad 560x, for example, does not cooperate with the memory
>   * detection code.)
>   */
> -static int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
> +static int __init copy_e820_map(struct e820entry * biosmap, unsigned int 
> nr_map)
>  {
>      /* Only one memory region (or negative)? Ignore it */

This comment is now stale.  I'd just drop the bit in brackets.

~Andrew

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