linux-kernel - Re: [PATCH v2] proc: fix races against execve() of /proc/PID/fd**

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Date:	Sun, 28 Aug 2011 13:31:56 +0400
From:	Vasiliy Kulikov <segoon@...nwall.com>
To:	Cyrill Gorcunov <gorcunov@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	kernel-hardening@...ts.openwall.com,
	Al Viro <viro@...iv.linux.org.uk>,
	David Rientjes <rientjes@...gle.com>,
	Stephen Wilson <wilsons@...rt.ca>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	linux-kernel@...r.kernel.org, security@...nel.org
Subject: Re: [PATCH v2] proc: fix races against execve() of /proc/PID/fd**

Hi Cyrill,

On Sun, Aug 28, 2011 at 13:25 +0400, Cyrill Gorcunov wrote:
> On Sat, Aug 27, 2011 at 11:01:47PM +0400, Vasiliy Kulikov wrote:
> ...
> >  
> > +static int proc_pid_fd_link_getattr(struct vfsmount *mnt, struct dentry *dentry,
> > +		struct kstat *stat)
> > +{
> > +	struct inode *inode = dentry->d_inode;
> > +	struct task_struct *task = get_proc_task(inode);
> > +	int rc;
> > +
> 
> Are we sure if the task will be always valid here?
> 
> 	if (!task)
> 		return -ENOENT;

No, you're right.  It needs (task == NULL) check.  Thank you!

-- 
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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