From: David Miller <davem@davemloft.net>
To: torvalds@linux-foundation.org
Cc: mathieu.desnoyers@efficios.com, linux-arch@vger.kernel.org,
axboe@kernel.dk, security@kernel.org, gregkh@linuxfoundation.org,
viro@zeniv.linux.org.uk, npiggin@kernel.dk
Subject: Re: [RFC PATCH (resend)] block layer zero-copy: missing access_ok() check
Date: Thu, 21 Mar 2013 17:33:13 -0400 (EDT) [thread overview]
Message-ID: <20130321.173313.827411684773319604.davem@davemloft.net> (raw)
In-Reply-To: <CA+55aFyrj9LsRp2gaoy1Lo6+s_brWjeKDG8F8JOLk2VaKndeaQ@mail.gmail.com>
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 15 Mar 2013 10:21:41 -0700
> Adding linux-arch. Guys, can you check your architectures?
...
>> * sparc: access_ok missing in get_user_pages_fast,
>> -> no indication of any _PAGE_USER flag.
Well, access_ok() returns 1 unconditionally on sparc64. I can add a
call there if you want. :-)
And that's because the user virtual address space is %100 segregated
from the privileged one. There are no "user address ranges"
vs. kernel ones.
For example, we can and do give 64-bit processes the full 64-bit
virtual address space for user mappings.
The page tables, outside of swapper_pg_dir, only map user pages.
prev parent reply other threads:[~2013-03-21 21:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20130315133748.GA31887@Krystal>
[not found] ` <20130315152326.GM31875@kernel.dk>
[not found] ` <20130315155808.GB1659@Krystal>
[not found] ` <CA+55aFxW0vkpgJCpJVJVqDmDG61P_AOoVMFVhfqVxM45Mj-LNA@mail.gmail.com>
[not found] ` <20130315171000.GA2342@Krystal>
2013-03-15 17:21 ` [RFC PATCH (resend)] block layer zero-copy: missing access_ok() check Linus Torvalds
2013-03-15 17:57 ` Mathieu Desnoyers
2013-03-15 18:01 ` Linus Torvalds
2013-03-15 18:04 ` Linus Torvalds
2013-03-15 18:07 ` Mathieu Desnoyers
2013-03-18 6:51 ` Benjamin Herrenschmidt
2013-03-21 21:33 ` David Miller [this message]
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