Re: [PATCH mig] Check that msgt_name is always smaller than 255.

[Samuel Thibault]

Applied, thanks!
Flavio Cruz, le mer. 10 mai 2023 01:39:54 -0400, a ecrit:
> For the x86_64 ABI we want this to always fit into 1 byte. Even for
> regular i686, msgt_name is always smaller than 25 (MACH_MSG_TYPE_LAST)
> and we don't have plans to have more names.
> 
> Also throw an error if we deemed an RPC to be "TooLong" as that won't
> work or work badly.
> 
> Tested by cross-compiling a basic Hurd system.
> ---
>  type.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/type.c b/type.c
> index 6158c14..253a194 100644
> --- a/type.c
> +++ b/type.c
> @@ -323,19 +323,21 @@ itUseLong(const ipc_type_t *it)
>      if ((it->itVarArray && !it->itInLine) || it->itIndefinite)
>       uselong = ShouldBeLong;
>  
> +    /* Check that msgt_name fits into 1 byte as the x86_64 ABI requires it.
> +       Note that MACH_MSG_TYPE_POLYMORPHIC is -1 hence it is ignored. */
>      if (((it->itInName != MACH_MSG_TYPE_POLYMORPHIC) &&
>        (it->itInName >= (1<<8))) ||
>       ((it->itOutName != MACH_MSG_TYPE_POLYMORPHIC) &&
> -      (it->itOutName >= (1<<8))) ||
> -     (it->itSize >= (1<<8)) ||
> +      (it->itOutName >= (1<<8)))) {
> +        error("Cannot have msgt_name greater than 255");
> +        uselong = TooLong;
> +    }
> +
> +     if ((it->itSize >= (1<<8)) ||
>       (it->itNumber >= (1<<12)))
>       uselong = MustBeLong;
>  
> -    if (((it->itInName != MACH_MSG_TYPE_POLYMORPHIC) &&
> -      (it->itInName >= (1<<16))) ||
> -     ((it->itOutName != MACH_MSG_TYPE_POLYMORPHIC) &&
> -      (it->itOutName >= (1<<16))) ||
> -     (it->itSize >= (1<<16)))
> +    if (it->itSize >= (1<<16))
>       uselong = TooLong;
>  
>      return uselong;
> @@ -416,7 +418,7 @@ itCheckDecl(identifier_t name, ipc_type_t *it)
>  
>      uselong = itUseLong(it);
>      if (uselong == TooLong)
> -     warn("%s: too big for mach_msg_type_long_t", name);
> +     error("%s: too big for mach_msg_type_long_t", name);
>      it->itLongForm = itCheckIsLong(it, it->itFlags,
>                                  (int)uselong >= (int)ShouldBeLong, name);
>  }
> -- 
> 2.39.2
> 
> 

-- 
Samuel
---
Pour une évaluation indépendante, transparente et rigoureuse !
Je soutiens la Commission d'Évaluation de l'Inria.