From: Arnd Bergmann <arnd@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
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Subject: Re: [PATCH v2 14/18] lib/test_lockup: fix kernel pointer check for separate address spaces
Date: Fri, 18 Feb 2022 08:15:42 +0100 [thread overview]
Message-ID: <CAK8P3a31_zG7npZbPHGixOYL0p28dGzs3f9ku_RB4p1tiEY0Tw@mail.gmail.com> (raw)
In-Reply-To: <20220218063549.GJ22576@lst.de>
On Fri, Feb 18, 2022 at 7:35 AM Christoph Hellwig <hch@lst.de> wrote:
>
> On Wed, Feb 16, 2022 at 02:13:28PM +0100, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > test_kernel_ptr() uses access_ok() to figure out if a given address
> > points to user space instead of kernel space. However on architectures
> > that set CONFIG_ALTERNATE_USER_ADDRESS_SPACE, a pointer can be valid
> > for both, and the check always fails because access_ok() returns true.
> >
> > Make the check for user space pointers conditional on the type of
> > address space layout.
>
> What is this code even trying to do? It looks extremly broken.
As I understand it, this is only meant for debugging, and the module contains
intentionally broken lock usage to test whether the watchdog and lockup
detection in the kernel is able to find them.
I did not try that hard to understand how it works though.
Arnd
next prev parent reply other threads:[~2022-02-18 7:16 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-16 13:13 [PATCH v2 00/18] clean up asm/uaccess.h, kill set_fs for good Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 01/18] uaccess: fix integer overflow on access_ok() Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 02/18] uaccess: fix nios2 and microblaze get_user_8() Arnd Bergmann
2022-02-16 13:35 ` David Laight
2022-02-18 6:25 ` Christoph Hellwig
2022-02-25 4:28 ` Dinh Nguyen
2022-02-16 13:13 ` [PATCH v2 03/18] nds32: fix access_ok() checks in get/put_user Arnd Bergmann
2022-02-18 6:25 ` Christoph Hellwig
2022-02-16 13:13 ` [PATCH v2 04/18] sparc64: add __{get,put}_kernel_nocheck() Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 05/18] x86: remove __range_not_ok() Arnd Bergmann
2022-02-18 6:28 ` Christoph Hellwig
2022-02-18 7:29 ` Arnd Bergmann
2022-02-18 15:45 ` David Laight
2022-02-16 13:13 ` [PATCH v2 06/18] x86: use more conventional access_ok() definition Arnd Bergmann
2022-02-18 6:29 ` Christoph Hellwig
2022-02-16 13:13 ` [PATCH v2 07/18] nios2: drop access_ok() check from __put_user() Arnd Bergmann
2022-02-18 6:29 ` Christoph Hellwig
2022-02-23 23:30 ` Dinh Nguyen
2022-02-24 7:05 ` Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 08/18] uaccess: add generic __{get,put}_kernel_nofault Arnd Bergmann
2022-02-18 6:30 ` Christoph Hellwig
2022-02-18 8:55 ` Geert Uytterhoeven
2022-02-16 13:13 ` [PATCH v2 09/18] mips: use simpler access_ok() Arnd Bergmann
2022-02-21 13:24 ` Thomas Bogendoerfer
2022-02-21 14:31 ` Arnd Bergmann
2022-02-21 15:21 ` Thomas Bogendoerfer
2022-02-22 16:36 ` Thomas Bogendoerfer
2022-02-23 20:05 ` Linus Torvalds
2022-02-23 7:41 ` Thomas Bogendoerfer
2022-02-23 9:26 ` Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 10/18] m68k: fix access_ok for coldfire Arnd Bergmann
2022-02-18 6:30 ` Christoph Hellwig
2022-02-18 9:00 ` Geert Uytterhoeven
2022-02-18 9:24 ` Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 11/18] arm64: simplify access_ok() Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 12/18] uaccess: fix type mismatch warnings from access_ok() Arnd Bergmann
2022-02-18 6:31 ` Christoph Hellwig
2022-02-25 4:30 ` Dinh Nguyen
2022-02-16 13:13 ` [PATCH v2 13/18] uaccess: generalize access_ok() Arnd Bergmann
2022-02-17 7:52 ` Arnd Bergmann
2022-02-17 19:15 ` Andy Lutomirski
2022-02-18 7:16 ` Arnd Bergmann
2022-02-18 9:30 ` David Laight
2022-02-18 18:07 ` Andy Lutomirski
2022-02-18 6:34 ` Christoph Hellwig
2022-02-18 7:23 ` Arnd Bergmann
2022-02-18 9:04 ` Geert Uytterhoeven
2022-02-24 8:29 ` Stafford Horne
2022-02-24 8:41 ` Arnd Bergmann
2022-02-25 4:31 ` Dinh Nguyen
2022-02-16 13:13 ` [PATCH v2 14/18] lib/test_lockup: fix kernel pointer check for separate address spaces Arnd Bergmann
2022-02-18 6:35 ` Christoph Hellwig
2022-02-18 7:15 ` Arnd Bergmann [this message]
2022-02-16 13:13 ` [PATCH v2 15/18] sparc64: remove CONFIG_SET_FS support Arnd Bergmann
2022-02-16 18:34 ` Sam Ravnborg
2022-02-16 18:41 ` Sam Ravnborg
2022-02-16 22:01 ` Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 16/18] sh: " Arnd Bergmann
2022-02-18 6:36 ` Christoph Hellwig
2022-02-16 13:13 ` [PATCH v2 17/18] ia64: " Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 18/18] uaccess: drop maining CONFIG_SET_FS users Arnd Bergmann
2022-02-16 18:44 ` Sam Ravnborg
2022-02-16 22:02 ` Arnd Bergmann
2022-02-17 22:36 ` Eric W. Biederman
2022-02-18 6:37 ` Christoph Hellwig
2022-02-18 7:10 ` Arnd Bergmann
2022-02-24 8:45 ` Stafford Horne
2022-02-25 4:33 ` Dinh Nguyen
2022-02-17 7:20 ` [PATCH v2 00/18] clean up asm/uaccess.h, kill set_fs for good Christophe Leroy
2022-02-17 7:49 ` Arnd Bergmann
2022-02-18 2:21 ` Al Viro
2022-02-18 9:20 ` Arnd Bergmann
2022-02-18 1:50 ` Al Viro
2022-02-18 10:01 ` Christophe Leroy
2022-02-17 8:13 ` Arnd Bergmann
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