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

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Message-ID: <CACT4Y+Zdy+cyfZ2dqnbZMn3edVteuQTyTswjL83JquFbhcPpTA@mail.gmail.com>
Date:	Mon, 9 May 2016 07:46:31 +0200
From:	Dmitry Vyukov <dvyukov@...gle.com>
To:	Yury Norov <ynorov@...iumnetworks.com>
Cc:	"Luruo, Kuthonuzo" <kuthonuzo.luruo@....com>,
	"aryabinin@...tuozzo.com" <aryabinin@...tuozzo.com>,
	"glider@...gle.com" <glider@...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 Sun, May 8, 2016 at 11:17 AM, Yury Norov <ynorov@...iumnetworks.com> wrote:
> 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.


We use _RET_IP_ in other places in portable part of kasan.