From: Christoph Hellwig <hch@lst.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ulrich Drepper <drepper@redhat.com>,
Christoph Hellwig <hch@lst.de>,
viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 2/2] add f_flags to struct statfs(64)
Date: Wed, 7 Jul 2010 19:33:11 +0200 [thread overview]
Message-ID: <20100707173311.GA14608@lst.de> (raw)
In-Reply-To: <AANLkTimUrmzjeJM5b43eV0wp_i_uhii20q8XH6OEa9Vg@mail.gmail.com>
On Wed, Jul 07, 2010 at 10:31:37AM -0700, Linus Torvalds wrote:
> On Wed, Jul 7, 2010 at 10:11 AM, Ulrich Drepper <drepper@redhat.com> wrote:
> >
> > How does this work with old kernels which didn't initialize f_spare?
>
> Some of the compat layers (and older kernels) don't copy the f_spare
> values, so user space should clear the field before doing the system
> call, and you should be ok.
>
> There should be no actual _uninitialized_ values copied from the
> kernel. IOW, either the kernel writes zero, or it doesn't write
> anything at all. Anything else would be a security issue anyway (ie
> kernel stack data leak). Afaik, no kernel does that.
Sometime before 2.4.0 (I posted the exact release in the previous
thread) the kernel initalized unused fields to 0xff. So if we want to
support these kernels it is an issue.
next prev parent reply other threads:[~2010-07-07 17:33 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-07 16:53 [PATCH 2/2] add f_flags to struct statfs(64) Christoph Hellwig
2010-07-07 17:11 ` Ulrich Drepper
2010-07-07 17:31 ` Linus Torvalds
2010-07-07 17:33 ` Christoph Hellwig [this message]
2010-07-07 17:55 ` Miklos Szeredi
2010-07-07 18:06 ` Linus Torvalds
2010-07-07 18:50 ` Nick Piggin
2010-07-07 19:30 ` Linus Torvalds
2010-07-18 6:41 ` Christoph Hellwig
2010-07-18 17:03 ` Linus Torvalds
2010-07-07 18:16 ` Nick Piggin
-- strict thread matches above, loose matches on Subject: below --
2010-06-26 9:35 Christoph Hellwig
2010-06-26 9:56 ` Nick Piggin
2010-06-26 13:09 ` Christoph Hellwig
2010-06-26 13:16 ` Nick Piggin
2010-06-26 12:55 ` Neil Brown
2010-06-26 13:12 ` Christoph Hellwig
2010-06-27 7:55 ` Tao Ma
2010-06-27 9:20 ` Christoph Hellwig
2010-06-28 18:43 ` Andreas Dilger
2010-06-28 19:52 ` Ulrich Drepper
2010-06-28 20:07 ` Andreas Dilger
2010-06-29 8:57 ` Nick Piggin
2010-06-29 9:25 ` Christoph Hellwig
2010-06-29 9:59 ` Ulrich Drepper
2010-06-29 11:05 ` Nick Piggin
2010-06-29 12:57 ` Christoph Hellwig
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