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Date: Fri, 2 Nov 2001 14:42:36 -0800 (PST)
From: Ken Ashcraft <kash@Stanford.EDU>
To: Roman Zippel <zippel@linux-m68k.org>
cc: <linux-kernel@vger.kernel.org>, <engler@Stanford.EDU>
Subject: Re: null pointer questions
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> > 2. What happens if I pass a null pointer as the destination parameter
> > to copy_from_user?  Does copy_from_user handle it safely or will the
> > kernel seg fault?
>
> The kernel won't crash, but it might fail (depending on whether 0 is a
> valid user space address or not).

Why does it matter if 0 is a valid user space or not?  If I make the call

copy_from_user(0, user_ptr, 4);

the null pointer is the kernel address, not the user address.  Can you
clarify please?

Thanks
Ken

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