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From: Sergey Dyasli <sergey.dyasli@citrix.com>
To: Vlastimil Babka <vbabka@suse.cz>, <xen-devel@lists.xen.org>,
	<kasan-dev@googlegroups.com>, <linux-mm@kvack.org>,
	<linux-kernel@vger.kernel.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Alexander Potapenko <glider@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Juergen Gross <jgross@suse.com>,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	George Dunlap <george.dunlap@citrix.com>,
	Ross Lagerwall <ross.lagerwall@citrix.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Wei Liu <wei.liu@kernel.org>, "Paul Durrant" <paul@xen.org>,
	"sergey.dyasli@citrix.com >> Sergey Dyasli" 
	<sergey.dyasli@citrix.com>
Subject: Re: [PATCH v1 4/4] xen/netback: Fix grant copy across page boundary with KASAN
Date: Wed, 15 Jan 2020 11:02:59 +0000	[thread overview]
Message-ID: <e0663153-35e0-32ef-87a5-39189c440a3d@citrix.com> (raw)
In-Reply-To: <26c43c43-b303-938c-2f26-8e0144159e29@suse.cz>

On 09/01/2020 10:33, Vlastimil Babka wrote:
> On 1/8/20 4:21 PM, Sergey Dyasli wrote:
>> From: Ross Lagerwall <ross.lagerwall@citrix.com>
>>
>> When KASAN (or SLUB_DEBUG) is turned on, the normal expectation that
>> allocations are aligned to the next power of 2 of the size does not
>> hold.
>
> Hmm, really? They should after 59bb47985c1d ("mm, sl[aou]b: guarantee
> natural alignment for kmalloc(power-of-two)"), i.e. since 5.4.
>
> But actually the guarantee is only for precise power of two sizes given
> to kmalloc(). Allocations of sizes that end up using the 96 or 192 bytes
> kmalloc cache have no such guarantee. But those might then cross page
> boundary also without SLUB_DEBUG.

That's interesting to know. It's certainly not the case for 4.19 kernel
for which PV KASAN was initially developed. But I guess this means that
only patch description needs updating.

>
>> Therefore, handle grant copies that cross page boundaries.
>>
>> Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
>> Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>

--
Thanks,
Sergey

WARNING: multiple messages have this Message-ID (diff)
From: Sergey Dyasli <sergey.dyasli@citrix.com>
To: Vlastimil Babka <vbabka@suse.cz>, <xen-devel@lists.xen.org>,
	<kasan-dev@googlegroups.com>, <linux-mm@kvack.org>,
	<linux-kernel@vger.kernel.org>
Cc: Juergen Gross <jgross@suse.com>,
	"sergey.dyasli@citrix.com >> Sergey Dyasli"
	<sergey.dyasli@citrix.com>, Wei Liu <wei.liu@kernel.org>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Paul Durrant <paul@xen.org>,
	George Dunlap <george.dunlap@citrix.com>,
	Ross Lagerwall <ross.lagerwall@citrix.com>,
	Alexander Potapenko <glider@google.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [Xen-devel] [PATCH v1 4/4] xen/netback: Fix grant copy across page boundary with KASAN
Date: Wed, 15 Jan 2020 11:02:59 +0000	[thread overview]
Message-ID: <e0663153-35e0-32ef-87a5-39189c440a3d@citrix.com> (raw)
In-Reply-To: <26c43c43-b303-938c-2f26-8e0144159e29@suse.cz>

On 09/01/2020 10:33, Vlastimil Babka wrote:
> On 1/8/20 4:21 PM, Sergey Dyasli wrote:
>> From: Ross Lagerwall <ross.lagerwall@citrix.com>
>>
>> When KASAN (or SLUB_DEBUG) is turned on, the normal expectation that
>> allocations are aligned to the next power of 2 of the size does not
>> hold.
>
> Hmm, really? They should after 59bb47985c1d ("mm, sl[aou]b: guarantee
> natural alignment for kmalloc(power-of-two)"), i.e. since 5.4.
>
> But actually the guarantee is only for precise power of two sizes given
> to kmalloc(). Allocations of sizes that end up using the 96 or 192 bytes
> kmalloc cache have no such guarantee. But those might then cross page
> boundary also without SLUB_DEBUG.

That's interesting to know. It's certainly not the case for 4.19 kernel
for which PV KASAN was initially developed. But I guess this means that
only patch description needs updating.

>
>> Therefore, handle grant copies that cross page boundaries.
>>
>> Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
>> Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>

--
Thanks,
Sergey

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

  reply	other threads:[~2020-01-15 11:03 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-08 15:20 [PATCH v1 0/4] basic KASAN support for Xen PV domains Sergey Dyasli
2020-01-08 15:20 ` [Xen-devel] " Sergey Dyasli
2020-01-08 15:20 ` [PATCH v1 1/4] kasan: introduce set_pmd_early_shadow() Sergey Dyasli
2020-01-08 15:20   ` [Xen-devel] " Sergey Dyasli
2020-01-10 14:41   ` kbuild test robot
2020-01-10 14:41     ` kbuild test robot
2020-01-10 14:41     ` [Xen-devel] " kbuild test robot
2020-01-11  5:21   ` kbuild test robot
2020-01-11  5:21     ` kbuild test robot
2020-01-11  5:21     ` [Xen-devel] " kbuild test robot
2020-01-15 10:54   ` Sergey Dyasli
2020-01-15 10:54     ` [Xen-devel] " Sergey Dyasli
2020-01-15 10:54     ` Sergey Dyasli
2020-01-15 11:09     ` Jürgen Groß
2020-01-15 11:09       ` [Xen-devel] " Jürgen Groß
2020-01-15 16:32       ` Sergey Dyasli
2020-01-15 16:32         ` [Xen-devel] " Sergey Dyasli
2020-01-15 16:32         ` Sergey Dyasli
2020-01-16  7:54         ` Jürgen Groß
2020-01-16  7:54           ` [Xen-devel] " Jürgen Groß
2020-01-08 15:20 ` [PATCH v1 2/4] x86/xen: add basic KASAN support for PV kernel Sergey Dyasli
2020-01-08 15:20   ` [Xen-devel] " Sergey Dyasli
2020-01-09  9:15   ` Jürgen Groß
2020-01-09  9:15     ` [Xen-devel] " Jürgen Groß
2020-01-10 11:07     ` Sergey Dyasli
2020-01-10 11:07       ` [Xen-devel] " Sergey Dyasli
2020-01-10 11:07       ` Sergey Dyasli
2020-01-09 23:27   ` Boris Ostrovsky
2020-01-09 23:27     ` [Xen-devel] " Boris Ostrovsky
2020-01-10 11:46     ` Sergey Dyasli
2020-01-10 11:46       ` [Xen-devel] " Sergey Dyasli
2020-01-10 11:46       ` Sergey Dyasli
2020-01-10 13:05   ` kbuild test robot
2020-01-10 13:05     ` kbuild test robot
2020-01-10 13:05     ` [Xen-devel] " kbuild test robot
2020-01-10 17:19   ` kbuild test robot
2020-01-10 17:19     ` kbuild test robot
2020-01-10 17:19     ` [Xen-devel] " kbuild test robot
2020-01-08 15:20 ` [PATCH v1 3/4] xen: teach KASAN about grant tables Sergey Dyasli
2020-01-08 15:20   ` [Xen-devel] " Sergey Dyasli
2020-01-08 15:21 ` [PATCH v1 4/4] xen/netback: Fix grant copy across page boundary with KASAN Sergey Dyasli
2020-01-08 15:21   ` [Xen-devel] " Sergey Dyasli
2020-01-09 10:33   ` Vlastimil Babka
2020-01-09 10:33     ` [Xen-devel] " Vlastimil Babka
2020-01-15 11:02     ` Sergey Dyasli [this message]
2020-01-15 11:02       ` Sergey Dyasli
2020-01-15 11:02       ` Sergey Dyasli
2020-01-09 13:36   ` Paul Durrant
2020-01-09 13:36     ` [Xen-devel] " Paul Durrant
2020-01-09 13:36     ` Paul Durrant
2020-01-10 14:27     ` Sergey Dyasli
2020-01-10 14:27       ` [Xen-devel] " Sergey Dyasli
2020-01-10 14:27       ` Sergey Dyasli

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