From: dvyukov@google.com (Dmitry Vyukov)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 06/11] change memory_is_poisoned_16 for aligned error
Date: Thu, 12 Oct 2017 09:16:39 +0200 [thread overview]
Message-ID: <CACT4Y+Ym3kq5RZ-4F=f97bvT2pNpzDf0kerf6tebzLOY_crR8Q@mail.gmail.com> (raw)
In-Reply-To: <20171011162345.f601c29d12c81af85bf38565@linux-foundation.org>
On Thu, Oct 12, 2017 at 1:23 AM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Wed, 11 Oct 2017 16:22:22 +0800 Abbott Liu <liuwenliang@huawei.com> wrote:
>
>> Because arm instruction set don't support access the address which is
>> not aligned, so must change memory_is_poisoned_16 for arm.
>>
>> ...
>>
>> --- a/mm/kasan/kasan.c
>> +++ b/mm/kasan/kasan.c
>> @@ -149,6 +149,25 @@ static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
>> return memory_is_poisoned_1(addr + size - 1);
>> }
>>
>> +#ifdef CONFIG_ARM
>> +static __always_inline bool memory_is_poisoned_16(unsigned long addr)
>> +{
>> + u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr);
>> +
>> + if (unlikely(shadow_addr[0] || shadow_addr[1])) return true;
>
> Coding-style is messed up. Please use scripts/checkpatch.pl.
>
>> + else {
>> + /*
>> + * If two shadow bytes covers 16-byte access, we don't
>> + * need to do anything more. Otherwise, test the last
>> + * shadow byte.
>> + */
>> + if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
>> + return false;
>> + return memory_is_poisoned_1(addr + 15);
>> + }
>> +}
>> +
>> +#else
>> static __always_inline bool memory_is_poisoned_16(unsigned long addr)
>> {
>> u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
>> @@ -159,6 +178,7 @@ static __always_inline bool memory_is_poisoned_16(unsigned long addr)
>>
>> return *shadow_addr;
>> }
>> +#endif
>
> - I don't understand why this is necessary. memory_is_poisoned_16()
> already handles unaligned addresses?
>
> - If it's needed on ARM then presumably it will be needed on other
> architectures, so CONFIG_ARM is insufficiently general.
>
> - If the present memory_is_poisoned_16() indeed doesn't work on ARM,
> it would be better to generalize/fix it in some fashion rather than
> creating a new variant of the function.
Yes, I think it will be better to fix the current function rather then
have 2 slightly different copies with ifdef's.
Will something along these lines work for arm? 16-byte accesses are
not too common, so it should not be a performance problem. And
probably modern compilers can turn 2 1-byte checks into a 2-byte check
where safe (x86).
static __always_inline bool memory_is_poisoned_16(unsigned long addr)
{
u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr);
if (shadow_addr[0] || shadow_addr[1])
return true;
/* Unaligned 16-bytes access maps into 3 shadow bytes. */
if (unlikely(!IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
return memory_is_poisoned_1(addr + 15);
return false;
}
next prev parent reply other threads:[~2017-10-12 7:16 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-11 8:22 [PATCH 00/11] KASan for arm Abbott Liu
2017-10-11 8:22 ` [PATCH 01/11] Initialize the mapping of KASan shadow memory Abbott Liu
2017-10-11 19:39 ` Florian Fainelli
2017-10-11 21:41 ` Russell King - ARM Linux
2017-10-17 13:28 ` Liuwenliang (Lamb)
2017-10-11 23:42 ` Dmitry Osipenko
2017-10-19 6:52 ` Liuwenliang (Lamb)
2017-10-19 12:01 ` Russell King - ARM Linux
2018-02-26 13:09 ` 答复: " Liuwenliang (Abbott Liu)
2017-10-12 7:58 ` Marc Zyngier
2017-11-09 7:46 ` Liuwenliang (Abbott Liu)
2017-11-09 10:10 ` Marc Zyngier
2017-11-15 10:20 ` Liuwenliang (Abbott Liu)
2017-11-15 10:35 ` Marc Zyngier
2017-11-15 13:16 ` Liuwenliang (Abbott Liu)
2017-11-15 13:54 ` Marc Zyngier
2017-11-16 3:07 ` Liuwenliang (Abbott Liu)
2017-11-16 9:54 ` Marc Zyngier
2017-11-16 14:24 ` Liuwenliang (Abbott Liu)
2017-11-16 14:40 ` Marc Zyngier
2017-11-17 1:39 ` 答复: " Liuwenliang (Abbott Liu)
2017-11-17 7:18 ` Liuwenliang (Abbott Liu)
2017-11-17 7:35 ` Christoffer Dall
2017-11-18 10:40 ` Liuwenliang (Abbott Liu)
2017-11-18 13:48 ` Marc Zyngier
2017-11-21 7:59 ` 答复: " Liuwenliang (Abbott Liu)
2017-11-21 9:40 ` Russell King - ARM Linux
2017-11-21 9:46 ` Marc Zyngier
2017-11-21 12:29 ` Mark Rutland
2017-11-22 12:56 ` Liuwenliang (Abbott Liu)
2017-11-22 13:06 ` Marc Zyngier
2017-11-23 1:54 ` Liuwenliang (Abbott Liu)
2017-11-23 15:22 ` Russell King - ARM Linux
2017-11-27 1:23 ` Liuwenliang (Abbott Liu)
2017-11-23 15:31 ` Mark Rutland
2017-11-27 1:26 ` 答复: " Liuwenliang (Abbott Liu)
2017-10-19 11:09 ` Russell King - ARM Linux
2018-02-24 14:28 ` Liuwenliang (Abbott Liu)
2017-10-11 8:22 ` [PATCH 02/11] replace memory function Abbott Liu
2017-10-19 12:05 ` Russell King - ARM Linux
2017-10-22 12:42 ` 答复: " Liuwenliang (Lamb)
2017-10-11 8:22 ` [PATCH 03/11] arm: Kconfig: enable KASan Abbott Liu
2017-10-11 19:15 ` Florian Fainelli
2017-10-19 12:34 ` Russell King - ARM Linux
2017-10-22 12:27 ` Liuwenliang (Lamb)
2017-10-11 8:22 ` [PATCH 04/11] Define the virtual space of KASan's shadow region Abbott Liu
2017-10-14 11:41 ` kbuild test robot
2017-10-16 11:42 ` Liuwenliang (Lamb)
2017-10-16 12:14 ` Ard Biesheuvel
2017-10-17 11:27 ` Liuwenliang (Lamb)
2017-10-17 11:52 ` Ard Biesheuvel
2017-10-17 13:02 ` Liuwenliang (Lamb)
2017-10-19 12:43 ` Russell King - ARM Linux
2017-10-22 12:12 ` Liuwenliang (Lamb)
2017-10-19 12:41 ` Russell King - ARM Linux
2017-10-19 12:40 ` Russell King - ARM Linux
2017-10-11 8:22 ` [PATCH 05/11] Disable kasan's instrumentation Abbott Liu
2017-10-11 19:16 ` Florian Fainelli
2017-10-19 12:47 ` Russell King - ARM Linux
2017-11-15 10:19 ` Liuwenliang (Abbott Liu)
2017-10-11 8:22 ` [PATCH 06/11] change memory_is_poisoned_16 for aligned error Abbott Liu
2017-10-11 23:23 ` Andrew Morton
2017-10-12 7:16 ` Dmitry Vyukov [this message]
2017-10-12 11:27 ` Liuwenliang (Lamb)
2017-10-19 12:51 ` Russell King - ARM Linux
2017-12-05 14:19 ` Liuwenliang (Abbott Liu)
2017-12-05 17:08 ` Ard Biesheuvel
2017-10-11 8:22 ` [PATCH 07/11] Avoid cleaning the KASan shadow area's mapping table Abbott Liu
2017-10-11 8:22 ` [PATCH 08/11] Add support arm LPAE Abbott Liu
2017-10-11 8:22 ` [PATCH 09/11] Don't need to map the shadow of KASan's shadow memory Abbott Liu
2017-10-19 12:55 ` Russell King - ARM Linux
2017-10-22 12:31 ` Liuwenliang (Lamb)
2017-10-11 8:22 ` [PATCH 10/11] Change mapping of kasan_zero_page int readonly Abbott Liu
2017-10-11 19:19 ` Florian Fainelli
2017-10-11 8:22 ` [PATCH 11/11] Add KASan layout Abbott Liu
2017-10-11 19:13 ` [PATCH 00/11] KASan for arm Florian Fainelli
2017-10-11 19:50 ` Florian Fainelli
[not found] ` <44c86924-930b-3eff-55b8-b02c9060ebe3@gmail.com>
2017-10-11 22:10 ` Laura Abbott
2017-10-11 22:58 ` Russell King - ARM Linux
2017-10-17 12:41 ` Liuwenliang (Lamb)
2017-10-12 4:55 ` Liuwenliang (Lamb)
2017-10-12 7:38 ` Arnd Bergmann
2017-10-17 1:04 ` 答复: " Liuwenliang (Lamb)
2018-02-13 18:40 ` Florian Fainelli
2018-02-23 2:10 ` Liuwenliang (Abbott Liu)
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