From: a.ryabinin@samsung•com (Andrey Ryabinin)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC/PATCH RESEND -next 14/21] mm: slub: kasan: disable kasan when touching unaccessible memory
Date: Tue, 15 Jul 2014 13:51:23 +0400 [thread overview]
Message-ID: <53C4F99B.5010007@samsung.com> (raw)
In-Reply-To: <20140715081852.GL11317@js1304-P5Q-DELUXE>
On 07/15/14 12:18, Joonsoo Kim wrote:
> On Tue, Jul 15, 2014 at 11:37:56AM +0400, Andrey Ryabinin wrote:
>> On 07/15/14 10:04, Joonsoo Kim wrote:
>>> On Wed, Jul 09, 2014 at 03:30:08PM +0400, Andrey Ryabinin wrote:
>>>> Some code in slub could validly touch memory marked by kasan as unaccessible.
>>>> Even though slub.c doesn't instrumented, functions called in it are instrumented,
>>>> so to avoid false positive reports such places are protected by
>>>> kasan_disable_local()/kasan_enable_local() calls.
>>>>
>>>> Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung•com>
>>>> ---
>>>> mm/slub.c | 21 +++++++++++++++++++--
>>>> 1 file changed, 19 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/mm/slub.c b/mm/slub.c
>>>> index 6ddedf9..c8dbea7 100644
>>>> --- a/mm/slub.c
>>>> +++ b/mm/slub.c
>>>> @@ -560,8 +560,10 @@ static void print_tracking(struct kmem_cache *s, void *object)
>>>> if (!(s->flags & SLAB_STORE_USER))
>>>> return;
>>>>
>>>> + kasan_disable_local();
>>>> print_track("Allocated", get_track(s, object, TRACK_ALLOC));
>>>> print_track("Freed", get_track(s, object, TRACK_FREE));
>>>> + kasan_enable_local();
>>>
>>> I don't think that this is needed since print_track() doesn't call
>>> external function with object pointer. print_track() call pr_err(), but,
>>> before calling, it retrieve t->addrs[i] so memory access only occurs
>>> in slub.c.
>>>
>> Agree.
>>
>>>> }
>>>>
>>>> static void print_page_info(struct page *page)
>>>> @@ -604,6 +606,8 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
>>>> unsigned int off; /* Offset of last byte */
>>>> u8 *addr = page_address(page);
>>>>
>>>> + kasan_disable_local();
>>>> +
>>>> print_tracking(s, p);
>>>>
>>>> print_page_info(page);
>>>> @@ -632,6 +636,8 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
>>>> /* Beginning of the filler is the free pointer */
>>>> print_section("Padding ", p + off, s->size - off);
>>>>
>>>> + kasan_enable_local();
>>>> +
>>>> dump_stack();
>>>> }
>>>
>>> And, I recommend that you put this hook on right place.
>>> At a glance, the problematic function is print_section() which have
>>> external function call, print_hex_dump(), with object pointer.
>>> If you disable kasan in print_section, all the below thing won't be
>>> needed, I guess.
>>>
>>
>> Nope, at least memchr_inv() call in slab_pad_check will be a problem.
>>
>> I think putting disable/enable only where we strictly need them might be a problem for future maintenance of slub.
>> If someone is going to add a new function call somewhere, he must ensure that it this call won't be a problem
>> for kasan.
>
> I don't agree with this.
>
> If someone is going to add a slab_pad_check() in other places in
> slub.c, we should disable/enable kasan there, too. This looks same
> maintenance problem to me. Putting disable/enable only where we
> strictly need at least ensures that we don't need to care when using
> slub internal functions.
>
> And, if memchr_inv() is problem, I think that you also need to add hook
> into validate_slab_cache().
>
> validate_slab_cache() -> validate_slab_slab() -> validate_slab() ->
> check_object() -> check_bytes_and_report() -> memchr_inv()
>
> Thanks.
>
Ok, you convinced me. I'll do it.
next prev parent reply other threads:[~2014-07-15 9:51 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-09 11:29 [RFC/PATCH RESEND -next 00/21] Address sanitizer for kernel (kasan) - dynamic memory error detector Andrey Ryabinin
2014-07-09 11:29 ` [RFC/PATCH RESEND -next 01/21] Add kernel address sanitizer infrastructure Andrey Ryabinin
2014-07-09 14:26 ` Christoph Lameter
2014-07-10 7:31 ` Andrey Ryabinin
2014-07-09 19:29 ` Andi Kleen
2014-07-09 20:40 ` Yuri Gribov
2014-07-10 12:10 ` Andrey Ryabinin
2014-07-09 20:26 ` Dave Hansen
2014-07-10 12:12 ` Andrey Ryabinin
2014-07-10 15:55 ` Dave Hansen
2014-07-10 19:48 ` Andrey Ryabinin
2014-07-10 20:04 ` Dave Hansen
2014-07-09 20:37 ` Dave Hansen
2014-07-09 20:38 ` Dave Hansen
2014-07-10 11:55 ` Sasha Levin
2014-07-10 13:01 ` Andrey Ryabinin
2014-07-10 13:31 ` Sasha Levin
2014-07-10 13:39 ` Andrey Ryabinin
2014-07-10 14:02 ` Sasha Levin
2014-07-10 19:04 ` Andrey Ryabinin
2014-07-10 13:50 ` Andrey Ryabinin
2014-07-09 11:29 ` [RFC/PATCH RESEND -next 02/21] init: main: initialize kasan's shadow area on boot Andrey Ryabinin
2014-07-09 11:29 ` [RFC/PATCH RESEND -next 03/21] x86: add kasan hooks fort memcpy/memmove/memset functions Andrey Ryabinin
2014-07-09 19:31 ` Andi Kleen
2014-07-10 13:54 ` Andrey Ryabinin
2014-07-09 11:29 ` [RFC/PATCH RESEND -next 04/21] x86: boot: vdso: disable instrumentation for code not linked with kernel Andrey Ryabinin
2014-07-09 11:29 ` [RFC/PATCH RESEND -next 05/21] x86: cpu: don't sanitize early stages of a secondary CPU boot Andrey Ryabinin
2014-07-09 19:33 ` Andi Kleen
2014-07-10 13:15 ` Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 06/21] x86: mm: init: allocate shadow memory for kasan Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 07/21] x86: Kconfig: enable kernel address sanitizer Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 08/21] mm: page_alloc: add kasan hooks on alloc and free pathes Andrey Ryabinin
2014-07-15 5:52 ` Joonsoo Kim
2014-07-15 6:54 ` Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 09/21] mm: Makefile: kasan: don't instrument slub.c and slab_common.c files Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 10/21] mm: slab: share virt_to_cache() between slab and slub Andrey Ryabinin
2014-07-15 5:53 ` Joonsoo Kim
2014-07-15 6:56 ` Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 11/21] mm: slub: share slab_err and object_err functions Andrey Ryabinin
2014-07-09 14:29 ` Christoph Lameter
2014-07-10 7:41 ` Andrey Ryabinin
2014-07-10 14:07 ` Christoph Lameter
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 12/21] mm: util: move krealloc/kzfree to slab_common.c Andrey Ryabinin
2014-07-09 14:32 ` Christoph Lameter
2014-07-10 7:43 ` Andrey Ryabinin
2014-07-10 14:08 ` Christoph Lameter
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 13/21] mm: slub: add allocation size field to struct kmem_cache Andrey Ryabinin
2014-07-09 14:33 ` Christoph Lameter
2014-07-10 8:44 ` Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 14/21] mm: slub: kasan: disable kasan when touching unaccessible memory Andrey Ryabinin
2014-07-15 6:04 ` Joonsoo Kim
2014-07-15 7:37 ` Andrey Ryabinin
2014-07-15 8:18 ` Joonsoo Kim
2014-07-15 9:51 ` Andrey Ryabinin [this message]
2014-07-15 14:26 ` Christoph Lameter
2014-07-15 15:02 ` Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 15/21] mm: slub: add kernel address sanitizer hooks to slub allocator Andrey Ryabinin
2014-07-09 14:48 ` Christoph Lameter
2014-07-10 9:24 ` Andrey Ryabinin
2014-07-15 6:09 ` Joonsoo Kim
2014-07-15 7:45 ` Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 16/21] arm: boot: compressed: disable kasan's instrumentation Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 17/21] arm: add kasan hooks fort memcpy/memmove/memset functions Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 18/21] arm: mm: reserve shadow memory for kasan Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 19/21] arm: Kconfig: enable kernel address sanitizer Andrey Ryabinin
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 20/21] fs: dcache: manually unpoison dname after allocation to shut up kasan's reports Andrey Ryabinin
2014-07-15 6:12 ` Joonsoo Kim
2014-07-15 6:08 ` Dmitry Vyukov
2014-07-15 9:34 ` Andrey Ryabinin
2014-07-15 9:45 ` Dmitry Vyukov
2014-07-09 11:30 ` [RFC/PATCH RESEND -next 21/21] lib: add kmalloc_bug_test module Andrey Ryabinin
2014-07-09 21:19 ` [RFC/PATCH RESEND -next 00/21] Address sanitizer for kernel (kasan) - dynamic memory error detector Dave Hansen
2014-07-09 21:44 ` Andi Kleen
2014-07-09 21:59 ` Vegard Nossum
2014-07-09 23:33 ` Dave Hansen
2014-07-10 0:03 ` Andi Kleen
2014-07-10 13:59 ` Andrey Ryabinin
[not found] ` <1421859105-25253-1-git-send-email-a.ryabinin@samsung.com>
2015-01-21 16:51 ` [PATCH v9 14/17] mm: vmalloc: pass additional vm_flags to __vmalloc_node_range() Andrey Ryabinin
[not found] ` <1422544321-24232-1-git-send-email-a.ryabinin@samsung.com>
2015-01-29 15:11 ` [PATCH v10 " Andrey Ryabinin
[not found] ` <1422985392-28652-1-git-send-email-a.ryabinin@samsung.com>
2015-02-03 17:43 ` [PATCH v11 16/19] " Andrey Ryabinin
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