Re: [PATCH 05/16] hw/uefi: add var-service-core.c

[Laszlo Ersek]

On 11/22/23 17:30, Gerd Hoffmann wrote:
>   Hi,
> 
>> - in general, we should filter out surrogate code points, for any use.
>> any UCS2 string from the guest that contains a surrogate code point
>> should be considered invalid, and the request should be rejected based
>> just on that.
> 
> Something like this?

yes please (except I'd recommend s/outlaw/reject/ in the comment)

Thanks
laszlo

> 
> edk2 seems to be inconsistent with strings, sometimes they are expected
> to include a terminating '\0' char (most of the time), sometimes not
> (in variable policies for example).
> 
> gboolean uefi_str_is_valid(const uint16_t *str, size_t len,
>                            gboolean must_be_null_terminated)
> {
>     size_t pos = 0;
> 
>     for (;;) {
>         if (pos == len) {
>             if (must_be_null_terminated) {
>                 return false;
>             } else {
>                 return true;
>             }
>         }
>         switch (str[pos]) {
>         case 0:
>             /* end of string */
>             return true;
>             ;;
>         case 0xd800 ... 0xdfff:
>             /* outlaw surrogates */
>             return false;
>         default:
>             /* char is good, check next */
>             break;
>         }
>         pos++;
>     }
> }
> 
> take care,
>   Gerd
>