From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Rosen Penev <rosenp@gmail.com>, Alex Williamson <alex@shazbot.org>
Cc: kvm@vger.kernel.org, Kees Cook <kees@kernel.org>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
open list <linux-kernel@vger.kernel.org>,
open "list:KERNEL" HARDENING "(not" covered by other
"areas):Keyword:b__counted_by(_le|_be)?b"
<linux-hardening@vger.kernel.org>,
Leon Romanovsky <leon@kernel.org>
Subject: Re: [PATCH] vfio: pci: use kzalloc_flex
Date: Mon, 30 Mar 2026 17:46:09 -0600 [thread overview]
Message-ID: <37378f49-437f-438b-ad6c-d60480feb306@embeddedor.com> (raw)
In-Reply-To: <CAKxU2N8rpaLXXsD7sUvw3ffMe8JUREGc9ru_HX0r4Uw4RT_q1g@mail.gmail.com>
On 3/30/26 17:24, Rosen Penev wrote:
> On Mon, Mar 30, 2026 at 4:16 PM Alex Williamson <alex@shazbot.org> wrote:
>>
>> [Cc +Leon]
>>
>> On Wed, 25 Mar 2026 19:37:47 -0700
>> Rosen Penev <rosenp@gmail.com> wrote:
>>
>>> Simplify allocation by using a flexible array member and kzalloc_flex.
>>> Less memory management needed.
>>>
>>> Use __counted_by for extra runtime analysis. Move assignment to after
>>> allocation as required by __counted_by.
>>
>> I don't understand this statement, nr_ranges was previously set after
>> the allocation of phys_vec. The only reordering was relative to
>> setting vdev, but that appears arbitrary.
> Yes that one. My understanding is __counted_by mandates immediate
> assignment after allocation. Otherwise UBSAN complains.
Not true. However, it's best practice.
The requirement is that the _counter_ must be initialized before
the first reference to the flexible-array member.
-Gustavo
next prev parent reply other threads:[~2026-03-30 23:47 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-26 2:37 [PATCH] vfio: pci: use kzalloc_flex Rosen Penev
2026-03-30 22:19 ` Alex Williamson
2026-03-30 23:24 ` Rosen Penev
2026-03-30 23:46 ` Gustavo A. R. Silva [this message]
2026-03-31 0:18 ` Rosen Penev
2026-03-31 0:51 ` Gustavo A. R. Silva
2026-03-31 0:23 ` Alex Williamson
2026-03-31 5:11 ` Leon Romanovsky
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