linux-kernel - Re: [PATCH 0/2] mm: make copy_to_kernel_nofault() not fault on user addresses

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <5fa50d78-6764-4f99-87b3-7bd7edbeea5a@csgroup.eu>
Date: Mon, 2 Sep 2024 08:19:33 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Omar Sandoval <osandov@...ndov.com>, linux-mm@...ck.org,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: Christoph Hellwig <hch@....de>, x86@...nel.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 loongarch@...ts.linux.dev, linux-mips@...r.kernel.org,
 linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
 linux-um@...ts.infradead.org, kernel-team@...com
Subject: Re: [PATCH 0/2] mm: make copy_to_kernel_nofault() not fault on user
 addresses



Le 02/09/2024 à 07:31, Omar Sandoval a écrit :
> [Vous ne recevez pas souvent de courriers de osandov@...ndov.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
> 
> From: Omar Sandoval <osandov@...com>
> 
> Hi,
> 
> I hit a case where copy_to_kernel_nofault() will fault (lol): if the
> destination address is in userspace and x86 Supervisor Mode Access
> Prevention is enabled. Patch 2 has the details and the fix. Patch 1
> renames a helper function so that its use in patch 2 makes more sense.
> If the rename is too intrusive, I can drop it.

The name of the function is "copy_to_kernel". If the destination is a 
user address, it is not a copy to kernel but a copy to user and you 
already have the function copy_to_user() for that. copy_to_user() 
properly handles SMAP.

Christophe


> 
> Thanks,
> Omar
> 
> Omar Sandoval (2):
>    mm: rename copy_from_kernel_nofault_allowed() to
>      copy_kernel_nofault_allowed()
>    mm: make copy_to_kernel_nofault() not fault on user addresses
> 
>   arch/arm/mm/fault.c         |  2 +-
>   arch/loongarch/mm/maccess.c |  2 +-
>   arch/mips/mm/maccess.c      |  2 +-
>   arch/parisc/lib/memcpy.c    |  2 +-
>   arch/powerpc/mm/maccess.c   |  2 +-
>   arch/um/kernel/maccess.c    |  2 +-
>   arch/x86/mm/maccess.c       |  4 ++--
>   include/linux/uaccess.h     |  2 +-
>   mm/maccess.c                | 10 ++++++----
>   9 files changed, 15 insertions(+), 13 deletions(-)
> 
> --
> 2.46.0
> 
>