From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: Xishi Qiu <qiuxishi@huawei.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andrey Konovalov <adech.fo@gmail.com>,
Rusty Russell <rusty@rustcorp.com.au>,
Michal Marek <mmarek@suse.cz>,
zhongjiang@huawei.com
Cc: Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
ryabinin.a.a@gmail.com
Subject: Re: [PATCH V2] kasan: fix last shadow judgement in memory_is_poisoned_16()
Date: Wed, 9 Sep 2015 13:01:34 +0300 [thread overview]
Message-ID: <55F0037E.40308@virtuozzo.com> (raw)
In-Reply-To: <55EED09E.3010107@huawei.com>
On 09/08/2015 03:12 PM, Xishi Qiu wrote:
> The shadow which correspond 16 bytes memory may span 2 or 3 bytes. If the
> memory is aligned on 8, then the shadow takes only 2 bytes. So we check
> "shadow_first_bytes" is enough, and need not to call "memory_is_poisoned_1(addr + 15);".
> But the code "if (likely(!last_byte))" is wrong judgement.
>
> e.g. addr=0, so last_byte = 15 & KASAN_SHADOW_MASK = 7, then the code will
> continue to call "memory_is_poisoned_1(addr + 15);"
>
> Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
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WARNING: multiple messages have this Message-ID (diff)
From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: Xishi Qiu <qiuxishi@huawei.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andrey Konovalov <adech.fo@gmail.com>,
Rusty Russell <rusty@rustcorp.com.au>,
Michal Marek <mmarek@suse.cz>, <zhongjiang@huawei.com>
Cc: Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>, <ryabinin.a.a@gmail.com>
Subject: Re: [PATCH V2] kasan: fix last shadow judgement in memory_is_poisoned_16()
Date: Wed, 9 Sep 2015 13:01:34 +0300 [thread overview]
Message-ID: <55F0037E.40308@virtuozzo.com> (raw)
In-Reply-To: <55EED09E.3010107@huawei.com>
On 09/08/2015 03:12 PM, Xishi Qiu wrote:
> The shadow which correspond 16 bytes memory may span 2 or 3 bytes. If the
> memory is aligned on 8, then the shadow takes only 2 bytes. So we check
> "shadow_first_bytes" is enough, and need not to call "memory_is_poisoned_1(addr + 15);".
> But the code "if (likely(!last_byte))" is wrong judgement.
>
> e.g. addr=0, so last_byte = 15 & KASAN_SHADOW_MASK = 7, then the code will
> continue to call "memory_is_poisoned_1(addr + 15);"
>
> Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
next prev parent reply other threads:[~2015-09-09 10:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-08 12:12 [PATCH V2] kasan: fix last shadow judgement in memory_is_poisoned_16() Xishi Qiu
2015-09-08 12:12 ` Xishi Qiu
2015-09-09 6:40 ` long.wanglong
2015-09-09 6:40 ` long.wanglong
2015-09-09 7:43 ` Xishi Qiu
2015-09-09 7:43 ` Xishi Qiu
2015-09-09 8:10 ` long.wanglong
2015-09-09 8:10 ` long.wanglong
2015-09-09 8:30 ` Andrey Ryabinin
2015-09-09 8:30 ` Andrey Ryabinin
2015-09-09 10:01 ` Andrey Ryabinin [this message]
2015-09-09 10:01 ` Andrey Ryabinin
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