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From: Jon Smirl <jonsmirl@gmail.com>
To: lkml <linux-kernel@vger.kernel.org>, Greg KH <greg@kroah.com>
Subject: off by one in sysfs
Date: Sat, 11 Jun 2005 23:00:00 -0400	[thread overview]
Message-ID: <9e47339105061120007061d7b1@mail.gmail.com> (raw)

sysfs/file.c

static int 
fill_write_buffer(struct sysfs_buffer * buffer, const char __user *
buf, size_t count)
{
	int error;

	if (!buffer->page)
		buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
	if (!buffer->page)
		return -ENOMEM;

	if (count >= PAGE_SIZE)
		count = PAGE_SIZE - 1;
	error = copy_from_user(buffer->page,buf,count);
	buffer->needs_read_fill = 1;
	return error ? -EFAULT : count;
}

count = PAGE_SIZE - 1;
should be 
count = PAGE_SIZE;

Even if your are trying to zero terminate which is unneeded when there
is a count, the count still needs to include the zero otherwise it is
inconsistent when count is less than PAGE_SIZE. Why get a zero page
too?

My attribute is a color_map described by 255 lines of 15 chars plus \n.

-- 
Jon Smirl
jonsmirl@gmail.com

             reply	other threads:[~2005-06-12  3:00 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-06-12  3:00 Jon Smirl [this message]
2005-06-12 15:41 ` off by one in sysfs Jon Smirl
2005-06-14 21:06   ` Greg KH
2005-06-14 21:07 ` Greg KH
2005-06-14 21:21   ` Jon Smirl
2005-06-14 21:27     ` Greg KH

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