From: Kees Cook <keescook@chromium.org>
To: Uladzislau Rezki <urezki@gmail.com>
Cc: Topi Miettinen <toiwoton@gmail.com>,
linux-hardening@vger.kernel.org, akpm@linux-foundation.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andy Lutomirski <luto@kernel.org>, Jann Horn <jannh@google.com>,
Linux API <linux-api@vger.kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Mike Rapoport <rppt@kernel.org>
Subject: Re: [PATCH v4] mm/vmalloc: randomize vmalloc() allocations
Date: Mon, 15 Mar 2021 09:16:26 -0700 [thread overview]
Message-ID: <202103150914.4172D96@keescook> (raw)
In-Reply-To: <20210315122410.GA26784@pc636>
On Mon, Mar 15, 2021 at 01:24:10PM +0100, Uladzislau Rezki wrote:
> On Mon, Mar 15, 2021 at 11:04:42AM +0200, Topi Miettinen wrote:
> > What's the problem with that? It seems to me that nothing relies on specific
> > addresses of the chunks, so it should be possible to randomize these too.
> > Also the alignment is honored.
> >
> My concern are:
>
> - it is not a vmalloc allocator;
> - per-cpu allocator allocates chunks, thus it might be it happens only once. It does not allocate it often;
That's actually the reason to randomize it: if it always ends up in the
same place at every boot, it becomes a stable target for attackers.
> - changing it will likely introduce issues you are not aware of;
> - it is not supposed to be interacting with vmalloc allocator. Read the
> comment under pcpu_get_vm_areas();
>
> Therefore i propose just not touch it.
How about splitting it from this patch instead? Then it can get separate
testing, etc.
--
Kees Cook
next prev parent reply other threads:[~2021-03-15 16:17 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-09 13:57 [PATCH v4] mm/vmalloc: randomize vmalloc() allocations Topi Miettinen
2021-03-14 17:23 ` Uladzislau Rezki
2021-03-15 9:04 ` Topi Miettinen
2021-03-15 12:24 ` Uladzislau Rezki
2021-03-15 16:16 ` Kees Cook [this message]
2021-03-15 17:47 ` Uladzislau Rezki
2021-03-16 8:01 ` Topi Miettinen
2021-03-16 11:34 ` Uladzislau Rezki
2021-03-15 11:45 ` Topi Miettinen
2021-03-15 15:35 ` Uladzislau Rezki
2021-03-15 16:23 ` Topi Miettinen
2021-03-15 18:02 ` Uladzislau Rezki
2021-03-16 7:01 ` Topi Miettinen
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