linux-kernel - Re: [BUG] signal: sighand unprotected when accessed by /proc

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Message-ID: <alpine.DEB.2.10.1406032310560.3319@nanos>
Date:	Tue, 3 Jun 2014 23:12:48 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Steven Rostedt <rostedt@...dmis.org>
cc:	Oleg Nesterov <oleg@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Clark Williams <williams@...hat.com>,
	"Luis Claudio R. Goncalves" <lclaudio@...g.org>
Subject: Re: [BUG] signal: sighand unprotected when accessed by /proc



On Tue, 3 Jun 2014, Steven Rostedt wrote:

> On Tue, 3 Jun 2014 22:09:38 +0200
> Oleg Nesterov <oleg@...hat.com> wrote:
>  
> > > Now, if that lock is released and reused (I didn't trace other tasks
> > > allocating these locks), it reinitializes the lock->wait_list.
> > 
> > How? From where? This should be done by sighand_ctor() only?
> 
> This looks definitely like an -rt only bug and it's an obvious one at
> that :-p
> 
> Looking in mm/slub.c: slab_alloc_node() we have this:
> 
>         if (unlikely(gfpflags & __GFP_ZERO) && object)
>                 memset(object, 0, s->object_size);
> #ifdef CONFIG_PREEMPT_RT_FULL
>         if (unlikely(s->ctor) && object)
>                 s->ctor(object);
> #endif  

Looks like the usual git/quilt default artifact.
 
That's why I have 

       QUILT_PATCH_OPTS="--fuzz=0"

in my .quiltrc 

Thanks,

	tglx
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