linux-kernel - Re: [PATCH] ocfs2: Fix NULL pointer dereferrence in __ocfs2_change_file

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Message-Id: <20120620154252.7dc7a817.akpm@linux-foundation.org>
Date:	Wed, 20 Jun 2012 15:42:52 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Luis Henriques <luis.henriques@...onical.com>
Cc:	Bret Towe <magnade@...il.com>, linux-kernel@...r.kernel.org,
	ocfs2-devel@....oracle.com, mfasheh@...e.com, jlbec@...lplan.org,
	sunil.mushran@...cle.com
Subject: Re: [PATCH] ocfs2: Fix NULL pointer dereferrence in
 __ocfs2_change_file_space

On Wed, 20 Jun 2012 23:34:44 +0100
Luis Henriques <luis.henriques@...onical.com> wrote:

> As ocfs2_fallocate() will invoke __ocfs2_change_file_space() with a NULL
> as the first parameter (file), it may trigger a NULL pointer dereferrence
> due to a missing check.  See http://bugs.launchpad.net/bugs/1006012.
> 
> Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
> ---
>  fs/ocfs2/file.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index 6e39668..84822a4 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -1950,7 +1950,7 @@ static int __ocfs2_change_file_space(struct file *file, struct inode *inode,
>  	if (ret < 0)
>  		mlog_errno(ret);
>  
> -	if (file->f_flags & O_SYNC)
> +	if (file && (file->f_flags & O_SYNC))
>  		handle->h_sync = 1;
>  
>  	ocfs2_commit_trans(osb, handle);

OK, at least it can't hurt ;)  I tagged it for -stable backporting.

Please don't forget the cc's and Tested-by:s.  There are quite a lot of
people involved in that launchpad report and they may like to know
what's going on, and can perhaps provide useful testing and review
input.  But I don't have their email addresses.

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