linux-kernel - Re: [PATCH 2/2] xattr: prevent NULL ptr deref warnings in __simple_xattr

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Message-ID: <20121015131636.GD29956@redhat.com>
Date:	Mon, 15 Oct 2012 09:16:36 -0400
From:	Aristeu Rozanski <aris@...hat.com>
To:	Sasha Levin <levinsasha928@...il.com>
Cc:	Tejun Heo <tj@...nel.org>, dan.carpenter@...cle.com,
	fengguang.wu@...el.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] xattr: prevent NULL ptr deref warnings in
 __simple_xattr_set

Sasha,
On Tue, Oct 09, 2012 at 02:52:15PM -0400, Sasha Levin wrote:
> On 09/14/2012 04:58 PM, Aristeu Rozanski wrote:
> > On Fri, Sep 14, 2012 at 01:55:55PM -0700, Tejun Heo wrote:
> >> On Fri, Sep 14, 2012 at 01:54:34PM -0700, Tejun Heo wrote:
> >>> On Fri, Sep 14, 2012 at 09:35:54PM +0200, Sasha Levin wrote:
> >>>> Prevent warnings generated by smatch due to unchecked dereference of
> >>>> 'new_xattr' in __simple_xattr_set().
> >>>
> >>> Isn't this an actual bug w/ or w/o smatch?  Remove request (NULL
> >>> @value) w/o XATTR_REPLACE for an non-existent node would end up
> >>> calling list_add() on NULL, right?  If so, please collapse these two
> >>> patches and mention the actual bug instead of smatch warning.
> >>
> >> And can somebody please make that function less confusing? -
> >> restructuring / commenting whatever.  It's doing something simple.
> >> It's not supposed to be this confusing.
> > 
> > I'll work on that.
> > 
> 
> As it's still happening in linux-next, should I send a simple patch to fix it along
> with Tejun's comments? Or is the rewrite of __simple_xattr_set() behind the corner?

the problem isn't because of the way __simple_xattr_set(), but because
the fix took another route and wasn't present when you hit it last.

-- 
Aristeu

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