From: Kees Cook <keescook@chromium•org>
To: Christophe Leroy <christophe.leroy@csgroup•eu>
Cc: "luto@kernel•org" <luto@kernel•org>,
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Subject: Re: [PATCH v2 5/9] mm: Initialize struct vm_unmapped_area_info
Date: Tue, 27 Feb 2024 10:07:26 -0800 [thread overview]
Message-ID: <202402271004.7145FDB53F@keescook> (raw)
In-Reply-To: <94a2b919-e03b-4ade-b13e-7774849dc02b@csgroup.eu>
On Tue, Feb 27, 2024 at 07:02:59AM +0000, Christophe Leroy wrote:
>
>
> Le 26/02/2024 à 20:09, Rick Edgecombe a écrit :
> > Future changes will need to add a field to struct vm_unmapped_area_info.
> > This would cause trouble for any archs that don't initialize the
> > struct. Currently every user sets each field, so if new fields are
> > added, the core code parsing the struct will see garbage in the new
> > field.
> >
> > It could be possible to initialize the new field for each arch to 0, but
> > instead simply inialize the field with a C99 struct inializing syntax.
>
> Why doing a full init of the struct when all fields are re-written a few
> lines after ?
It's a nice change for robustness and makes future changes easier. It's
not actually wasteful since the compiler will throw away all redundant
stores.
> If I take the exemple of powerpc function slice_find_area_bottomup():
>
> struct vm_unmapped_area_info info;
>
> info.flags = 0;
> info.length = len;
> info.align_mask = PAGE_MASK & ((1ul << pshift) - 1);
> info.align_offset = 0;
But one cleanup that is possible from explicitly zero-initializing the
whole structure would be dropping all the individual "= 0" assignments.
:)
--
Kees Cook
next prev parent reply other threads:[~2024-02-27 18:08 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240226190951.3240433-1-rick.p.edgecombe@intel.com>
2024-02-26 19:09 ` [PATCH v2 5/9] mm: Initialize struct vm_unmapped_area_info Rick Edgecombe
2024-02-27 7:02 ` Christophe Leroy
2024-02-27 15:00 ` Edgecombe, Rick P
2024-02-27 18:07 ` Kees Cook [this message]
2024-02-27 18:16 ` Christophe Leroy
2024-02-27 20:25 ` Edgecombe, Rick P
2024-02-28 13:22 ` Christophe Leroy
2024-02-28 17:01 ` Edgecombe, Rick P
2024-02-28 23:10 ` Christophe Leroy
2024-02-28 17:21 ` Kees Cook
2024-03-02 0:47 ` Edgecombe, Rick P
2024-03-02 1:51 ` Kees Cook
2024-03-04 18:00 ` Christophe Leroy
2024-03-04 18:03 ` Edgecombe, Rick P
2024-02-28 11:51 ` Kirill A. Shutemov
[not found] ` <20240302001714.674091-1-rick.p.edgecombe@intel.com>
2024-03-02 0:17 ` [RFC v2.1 07/12] powerpc: Use initializer for " Rick Edgecombe
2024-03-05 0:51 ` Michael Ellerman
2024-03-05 14:50 ` Edgecombe, Rick P
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