From: Andrew Morton <akpm@osdl.org>
To: mason@suse.com, linux-kernel@vger.kernel.org, andrea@suse.de
Subject: Re: [RFC] copy_from_user races with readpage
Date: Wed, 19 Apr 2006 14:38:46 -0700 [thread overview]
Message-ID: <20060419143846.7fe9377a.akpm@osdl.org> (raw)
In-Reply-To: <20060419134148.262c61cd.akpm@osdl.org>
Andrew Morton <akpm@osdl.org> wrote:
>
> The application is being a bit silly, because the read will return
> indeterminate results depending on whether it gets there before or after
> the write. But that's assuming that the read is reading the part of the
> page which the writer is writing. If the reader is reading bytes 1000-1010
> and the writer is writing bytes 990-1000 then the reader is being non-silly
> and would be justifiably surprised to see zeroes.
>
No, that's wrong, isn't it? If the reader is reading parts of the page
which the writer isn't writing then __copy_from_user_inatomic() won't touch
that part of the page.
So it's only the SillyApp which we're dealing with here.
So hrm. Yes, I guess we should still fix it.
next prev parent reply other threads:[~2006-04-19 21:36 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-19 17:18 Chris Mason
2006-04-19 20:41 ` Andrew Morton
2006-04-19 21:38 ` Andrew Morton [this message]
2006-04-19 22:18 ` Neil Brown
2006-04-19 23:36 ` Andrea Arcangeli
2006-04-28 2:04 ` [PATCH INTRO] Re: [RFC] copy_from_user races with readpage, [PATCH 000 of 2] Introduction NeilBrown
2006-04-28 2:10 ` [PATCH 001 of 2] Prepare for __copy_from_user_inatomic to not zero missed bytes NeilBrown
2006-04-28 2:10 ` [PATCH 002 of 2] Make copy_from_user_inatomic NOT zero the tail on i386 NeilBrown
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