linux-kernel - Re: [PATCH v2 1/2] mm, kasan: improve double-free detection

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Message-ID: <20160508085045.GA27394@yury-N73SV>
Date:	Sun, 8 May 2016 12:17:02 +0300
From:	Yury Norov <ynorov@...iumnetworks.com>
To:	"Luruo, Kuthonuzo" <kuthonuzo.luruo@....com>
CC:	"aryabinin@...tuozzo.com" <aryabinin@...tuozzo.com>,
	"glider@...gle.com" <glider@...gle.com>,
	"dvyukov@...gle.com" <dvyukov@...gle.com>,
	"cl@...ux.com" <cl@...ux.com>,
	"penberg@...nel.org" <penberg@...nel.org>,
	"rientjes@...gle.com" <rientjes@...gle.com>,
	"iamjoonsoo.kim@....com" <iamjoonsoo.kim@....com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"kasan-dev@...glegroups.com" <kasan-dev@...glegroups.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"klimov.linux@...il.com" <klimov.linux@...il.com>
Subject: Re: [PATCH v2 1/2] mm, kasan: improve double-free detection

On Sat, May 07, 2016 at 03:15:59PM +0000, Luruo, Kuthonuzo wrote:
> Thank you for the review!
> 
> > > +	switch (alloc_data.state) {
> > > +	case KASAN_STATE_QUARANTINE:
> > > +	case KASAN_STATE_FREE:
> > > +		kasan_report((unsigned long)object, 0, false,
> > > +				(unsigned long)__builtin_return_address(1));
> > 
> > __builtin_return_address() is unsafe if argument is non-zero. Use
> > return_address() instead.
> 
> hmm, I/cscope can't seem to find an x86 implementation for return_address().
> Will dig further; thanks.
> 

It seems there's no generic interface to obtain return address. x86
has  working __builtin_return_address() and it's ok with it, others
use their own return_adderss(), and ok as well.

I think unification is needed here.