linux-kernel - [PATCH 0/2] Fix mmap bugs with sysfs_remove_bin

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Date:	Mon, 20 Sep 2010 00:55:33 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Greg Kroah-Hartman <gregkh@...e.de>
Cc:	<linux-kernel@...r.kernel.org>, Tejun Heo <tj@...nel.org>,
	Hugh Dickins <hughd@...gle.com>
Subject: [PATCH 0/2] Fix mmap bugs with sysfs_remove_bin_file

While reviewing the sysfs mmap code in fs/sysfs/bin.c I found two
rather nasty potential issues.

The first is if one of our wrapped mmap implementations implements
vma->close() we do not call it at sysfs_remove_bin_file time leading
to who knows what carnage.

The second is that we are potentially accessing the wrapped vm_ops
after sysfs_remove_bin_file has completed.   Which could be a problem
if it is a modular user.

I don't know of any real world instances of problems.  None of the
bin attribute mmaps functions that I know of today implement a close
method.  However it seems prudent to fix these now before we have
track down some mysterious weird failure with hotunplug.

Eric W. Biederman (2):
      sysfs: Fail bin file mmap if vma close is implemented.
      sysfs: only access bin file vm_ops with the active lock
---
 fs/sysfs/bin.c |   68 ++++++++++++++++++++++++++++----------------------------
 1 files changed, 34 insertions(+), 34 deletions(-)
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