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From: Masami Hiramatsu <mhiramat@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
	Christoph Hellwig <hch@lst.de>,
	"the arch/x86 maintainers" <x86@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-parisc@vger.kernel.org,
	linux-um <linux-um@lists.infradead.org>,
	Netdev <netdev@vger.kernel.org>,
	bpf@vger.kernel.org, Linux-MM <linux-mm@kvack.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 11/18] maccess: remove strncpy_from_unsafe
Date: Thu, 14 May 2020 18:44:19 +0900	[thread overview]
Message-ID: <20200514184419.0fbf548ccf883c097d94573a@kernel.org> (raw)
In-Reply-To: <CAHk-=wjP8ysEZnNFi_+E1ZEFGpcbAN8kbYHrCnC93TX6XX+jEQ@mail.gmail.com>

On Wed, 13 May 2020 19:43:24 -0700
Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Wed, May 13, 2020 at 6:00 PM Masami Hiramatsu <mhiramat@kernel.org> wrote:
> >
> > > But we should likely at least disallow it entirely on platforms where
> > > we really can't - or pick one hardcoded choice. On sparc, you really
> > > _have_ to specify one or the other.
> >
> > OK. BTW, is there any way to detect the kernel/user space overlap on
> > memory layout statically? If there, I can do it. (I don't like
> > "if (CONFIG_X86)" thing....)
> > Or, maybe we need CONFIG_ARCH_OVERLAP_ADDRESS_SPACE?
> 
> I think it would be better to have a CONFIG variable that
> architectures can just 'select' to show that they are ok with separate
> kernel and user addresses.
> 
> Because I don't think we have any way to say that right now as-is. You
> can probably come up with hacky ways to approximate it, ie something
> like
> 
>     if (TASK_SIZE_MAX > PAGE_OFFSET)
>         .... they overlap ..
> 
> which would almost work, but..

It seems TASK_SIZE_MAX is defined only on x86 and s390, what about
comparing STACK_TOP_MAX with PAGE_OFFSET ?
Anyway, I agree that the best way is introducing a CONFIG.

Thank you,

-- 
Masami Hiramatsu <mhiramat@kernel.org>

  reply	other threads:[~2020-05-14  9:44 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-13 16:00 clean up and streamline probe_kernel_* and friends v2 Christoph Hellwig
2020-05-13 16:00 ` [PATCH 01/18] maccess: unexport probe_kernel_write and probe_user_write Christoph Hellwig
2020-05-13 16:00 ` [PATCH 02/18] maccess: remove various unused weak aliases Christoph Hellwig
2020-05-13 16:00 ` [PATCH 03/18] maccess: remove duplicate kerneldoc comments Christoph Hellwig
2020-05-13 16:00 ` [PATCH 04/18] maccess: clarify " Christoph Hellwig
2020-05-13 16:00 ` [PATCH 05/18] maccess: update the top of file comment Christoph Hellwig
2020-05-13 16:00 ` [PATCH 06/18] maccess: rename strncpy_from_unsafe_user to strncpy_from_user_nofault Christoph Hellwig
2020-05-13 16:00 ` [PATCH 07/18] maccess: rename strncpy_from_unsafe_strict to strncpy_from_kernel_nofault Christoph Hellwig
2020-05-13 16:00 ` [PATCH 08/18] maccess: rename strnlen_unsafe_user to strnlen_user_nofault Christoph Hellwig
2020-05-13 16:00 ` [PATCH 09/18] maccess: remove probe_read_common and probe_write_common Christoph Hellwig
2020-05-13 16:00 ` [PATCH 10/18] maccess: unify the probe kernel arch hooks Christoph Hellwig
2020-05-14  1:13   ` Masami Hiramatsu
2020-05-19  5:46     ` Christoph Hellwig
2020-05-13 16:00 ` [PATCH 11/18] maccess: remove strncpy_from_unsafe Christoph Hellwig
2020-05-13 19:11   ` Linus Torvalds
2020-05-13 19:11     ` Linus Torvalds
2020-05-13 19:28     ` Christoph Hellwig
2020-05-13 22:36       ` Daniel Borkmann
2020-05-13 23:03         ` Linus Torvalds
2020-05-13 23:03           ` Linus Torvalds
2020-05-13 23:24           ` Daniel Borkmann
2020-05-13 23:20         ` Masami Hiramatsu
2020-05-13 23:59           ` Linus Torvalds
2020-05-13 23:59             ` Linus Torvalds
2020-05-14  1:00             ` Masami Hiramatsu
2020-05-14  2:43               ` Linus Torvalds
2020-05-14  2:43                 ` Linus Torvalds
2020-05-14  9:44                 ` Masami Hiramatsu [this message]
2020-05-14 10:27                   ` Daniel Borkmann
2020-05-13 23:28         ` Al Viro
2020-05-13 23:58           ` Daniel Borkmann
2020-05-14 10:01             ` David Laight
2020-05-14 10:21               ` Daniel Borkmann
2020-05-13 16:00 ` [PATCH 12/18] maccess: always use strict semantics for probe_kernel_read Christoph Hellwig
2020-05-13 16:00 ` [PATCH 13/18] maccess: move user access routines together Christoph Hellwig
2020-05-13 16:00 ` [PATCH 14/18] maccess: allow architectures to provide kernel probing directly Christoph Hellwig
2020-05-13 19:36   ` Linus Torvalds
2020-05-13 19:36     ` Linus Torvalds
2020-05-13 19:40     ` Christoph Hellwig
2020-05-13 19:48       ` Linus Torvalds
2020-05-13 19:48         ` Linus Torvalds
2020-05-13 19:54         ` Christoph Hellwig
2020-05-16  3:42   ` Masami Hiramatsu
2020-05-18 15:09     ` Christoph Hellwig
2020-05-13 16:00 ` [PATCH 15/18] x86: use non-set_fs based maccess routines Christoph Hellwig
2020-05-13 16:00 ` [PATCH 16/18] maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault Christoph Hellwig
2020-05-13 16:00 ` [PATCH 17/18] maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault Christoph Hellwig
2020-05-13 16:00 ` [PATCH 18/18] maccess: rename probe_kernel_address to get_kernel_nofault Christoph Hellwig
2020-05-13 19:37 ` clean up and streamline probe_kernel_* and friends v2 Linus Torvalds
2020-05-13 19:37   ` Linus Torvalds
2020-05-13 23:04 ` Daniel Borkmann
2020-05-13 23:20   ` Linus Torvalds
2020-05-13 23:20     ` Linus Torvalds
2020-05-19  5:50   ` Christoph Hellwig

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