From: Venu Byravarasu <vbyravarasu@nvidia.com>
To: Naotaka Hamaguchi <n.hamaguchi@jp.fujitsu.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Subject: RE: [PATCH] mm: mmap() sometimes succeeds even if the region to map is invalid.
Date: Fri, 17 Feb 2012 14:34:13 +0530 [thread overview]
Message-ID: <D958900912E20642BCBC71664EFECE3E6DD198A7AE@BGMAIL02.nvidia.com> (raw)
In-Reply-To: <4F3E1319.6050304@jp.fujitsu.com>
> The detail of these problems is as follows:
> 1. mmap() succeeds even if "offset" argument is a negative value, although
> it should return EINVAL in such case.
> In such case, it is actually regarded as big positive value
> because the type of "off" is "unsigned long" in the kernel.
> For example, off=-4096 (-0x1000) is regarded as
> off = 0xfffffffffffff000 (x86_64) and as off = 0xfffff000 (x86).
> It results in mapping too big offset region.
It is not true always.
Considering your example, say if page size is 4k, then PAGE_MASK = 0xFFF
hence (off & ~PAGE_MASK) will be true and " -EINVAL" will be returned.
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next prev parent reply other threads:[~2012-02-17 9:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-17 8:43 Naotaka Hamaguchi
2012-02-17 9:04 ` Venu Byravarasu [this message]
2012-02-20 7:23 ` Naotaka Hamaguchi
2012-02-18 2:00 ` Hugh Dickins
2012-02-21 8:30 ` Naotaka Hamaguchi
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