linux-kernel - Re: [PATCH v2 2.6.38-rc8-tip 7/20] 7: uprobes: store/restore original instruction.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20110315092247.GW24254@linux.vnet.ibm.com>
Date:	Tue, 15 Mar 2011 14:52:47 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Stephen Wilson <wilsons@...rt.ca>
Cc:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	Steven Rostedt <rostedt@...dmis.org>,
	Linux-mm <linux-mm@...ck.org>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Christoph Hellwig <hch@...radead.org>,
	Andi Kleen <andi@...stfloor.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Oleg Nesterov <oleg@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
	Roland McGrath <roland@...k.frob.com>,
	SystemTap <systemtap@...rces.redhat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [PATCH v2 2.6.38-rc8-tip 7/20]  7: uprobes: store/restore
 original instruction.

* Stephen Wilson <wilsons@...rt.ca> [2011-03-14 14:09:14]:

> On Mon, Mar 14, 2011 at 07:05:22PM +0530, Srikar Dronamraju wrote:
> >  static int install_uprobe(struct mm_struct *mm, struct uprobe *uprobe)
> >  {
> > -	int ret = 0;
> > +	struct task_struct *tsk;
> > +	int ret = -EINVAL;
> >  
> > -	/*TODO: install breakpoint */
> > -	if (!ret)
> > +	get_task_struct(mm->owner);
> > +	tsk = mm->owner;
> > +	if (!tsk)
> > +		return ret;
> 
> I think you need to check that tsk != NULL before calling
> get_task_struct()...
> 

Guess checking for tsk != NULL would only help if and only if we are doing
within rcu.  i.e we have to change to something like this

	rcu_read_lock()
	if (mm->owner) {
		get_task_struct(mm->owner)
		tsk = mm->owner;
	}
	rcu_read_unlock()
	if (!tsk)
		return ret;

Agree?

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/