Re: [PATCH v2 0/2] MR4108: Improve DMI tables under Linux.

[Jinoh Kang (＠iamahuman)]

Jinoh Kang (@iamahuman) commented about dlls/ntdll/unix/system.c:
> close( fd );
>      }
>  }
>
> +static void derive_machineid_to_uuid( GUID *uuid )
> +{
> +    static unsigned char wine_uuid[16] = { 0xe8, 0x65, 0x52, 0x8d, 0x0a, 0xa2, 0x45, 0x27,
> +                                           0xa8, 0x3b, 0x15, 0xed, 0x41, 0xb5, 0xd0, 0x91 };
> +    GUID machine_uuid;
> +    unsigned char out256[32]; /* returning first 128 bits only */
> +
> +    read_machine_id( &machine_uuid );
> +
> +    hmac_sha256( wine_uuid, sizeof(wine_uuid), (const unsigned char *)&machine_uuid, sizeof(machine_uuid), out256 );
> +
> +    memset( &machine_uuid, 0, sizeof(machine_uuid) );

This write is unused and will be optimized out by the compiler.

Are you looking for something like [`explicit_bzero(3)`](https://man7.org/linux/man-pages/man3/bzero.3.html)?  In that case, why is machine UUID considered sensitive enough to warrant erasure?

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/4108#note_49546