linux-kernel - Re: [RFC/PATCH RESEND -next 01/21] Add kernel address sanitizer infrastructure.

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: <53BEF1E5.2000502@intel.com>
Date:	Thu, 10 Jul 2014 13:04:53 -0700
From:	Dave Hansen <dave.hansen@...el.com>
To:	Andrey Ryabinin <ryabinin.a.a@...il.com>
CC:	Andrey Ryabinin <a.ryabinin@...sung.com>,
	linux-kernel@...r.kernel.org, Dmitry Vyukov <dvyukov@...gle.com>,
	Konstantin Serebryany <kcc@...gle.com>,
	Alexey Preobrazhensky <preobr@...gle.com>,
	Andrey Konovalov <adech.fo@...il.com>,
	Yuri Gribov <tetra2005@...il.com>,
	Konstantin Khlebnikov <koct9i@...il.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Michal Marek <mmarek@...e.cz>,
	Russell King <linux@....linux.org.uk>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Christoph Lameter <cl@...ux.com>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kbuild@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	x86@...nel.org, linux-mm@...ck.org
Subject: Re: [RFC/PATCH RESEND -next 01/21] Add kernel address sanitizer infrastructure.

On 07/10/2014 12:48 PM, Andrey Ryabinin wrote:
>>>> How does this interact with vmalloc() addresses or those from a kmap()?
>>>>
>>> It's used only for lowmem:
>>>
>>> static inline bool addr_is_in_mem(unsigned long addr)
>>> {
>>>       return likely(addr >= PAGE_OFFSET && addr < (unsigned long)high_memory);
>>> }
>>
>> That's fine, and definitely covers the common cases.  Could you make
>> sure to call this out explicitly?  Also, there's nothing to _keep_ this
>> approach working for things out of the direct map, right?  It would just
>> be a matter of updating the shadow memory to have entries for the other
>> virtual address ranges.
> 
> Why do you want shadow for things out of the direct map? If you want
> to catch use-after-free in vmalloc than DEBUG_PAGEALLOC will be
> enough. If you want catch out-of-bounds in vmalloc you don't need
> anything, because vmalloc allocates guarding hole in the end. Or do
> you want something else?

That's all true for page-size accesses.  Address sanitizer's biggest
advantage over using the page tables is that it can do checks at
sub-page granularity.  But, we don't have any APIs that I can think of
that _care_ about <PAGE_SIZE outside of the direct map (maybe zsmalloc,
but that's pretty obscure).

So I guess it doesn't matter.
--
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/