From: Helge Hafting <helge.hafting@hist.no>
To: Andrea Arcangeli <andrea@novell.com>
Cc: William Lee Irwin III <wli@holomorphy.com>,
Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org, an.li.wang@intel.com
Subject: Re: truncate shows non zero data beyond the end of the inode with MAP_SHARED
Date: Thu, 16 Sep 2004 10:49:33 +0200 [thread overview]
Message-ID: <4149539D.9070001@hist.no> (raw)
In-Reply-To: <20040915220819.GF15426@dualathlon.random>
Andrea Arcangeli wrote:
>On Wed, Sep 15, 2004 at 03:00:16PM -0700, William Lee Irwin III wrote:
>
>
>>William Lee Irwin III <wli@holomorphy.com> wrote:
>>
>>
>>>>Zeroing the final partial page during expanding truncate (flushing TLB)
>>>>sounds like a reasonable half measure; we don't do anything at the moment.
>>>>
>>>>
>>On Wed, Sep 15, 2004 at 02:55:24PM -0700, Andrew Morton wrote:
>>
>>
>>>Sure about that? block_truncate_page() gets called.
>>>
>>>
>>So it does; then the hard parts are what's biting aa.
>>
>>
>
>block_truncate_page is unrelated with this issue, it's called on the
>_new_ partial page generated by truncate, not on the _old_ partial page
>that is being extended to be a _full_ page (with garbage inside between
>the old_i_size and PAGE_ALIGN(old_i_size)).
>
>
Could this "garbage" possibly be confidential data?
I.e. one user repeatedly makes and mmaps a 1-byte file,
extends it to 4k, and looks at the 4095 bytes of "garbage".
Maybe he finds some "interesting stuff" when someone else's
confidential file just got dropped from pagecache
so he could mmap this 1-byte file?
Helge Hafting
next prev parent reply other threads:[~2004-09-16 8:44 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-15 12:29 truncate shows non zero data beyond the end of the inode with MAP_SHARED Andrea Arcangeli
2004-09-15 12:46 ` Alan Cox
2004-09-15 21:01 ` William Lee Irwin III
2004-09-15 21:55 ` Andrew Morton
2004-09-15 22:00 ` William Lee Irwin III
2004-09-15 22:08 ` Andrea Arcangeli
2004-09-16 8:49 ` Helge Hafting [this message]
2004-09-16 14:26 ` Andrea Arcangeli
2004-09-17 13:49 ` Helge Hafting
2004-09-17 13:52 ` Andrea Arcangeli
2004-09-17 13:54 ` William Lee Irwin III
2004-09-15 22:04 ` Andrea Arcangeli
2004-09-15 21:58 ` Andrea Arcangeli
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4149539D.9070001@hist.no \
--to=helge.hafting@hist.no \
--cc=akpm@osdl.org \
--cc=an.li.wang@intel.com \
--cc=andrea@novell.com \
--cc=linux-kernel@vger.kernel.org \
--cc=wli@holomorphy.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox