linux-kernel - Q: copy_*_user() with size==0

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Message-ID: <ygfr6pwydj8.fsf@janus.isnogud.escape.de>
Date:	04 May 2007 14:32:59 +0200
From:	Urs Thuermann <urs@...ogud.escape.de>
To:	linux-kernel@...r.kernel.org
Subject: Q: copy_*_user() with size==0

Reading the i386 source of copy_to_user() and reading some instances
of how it's used, it seems valid to pass 0 for the size argument and
that kernel address pointers, i.e. the @from argument in
copy_to_user() and the @to argument in copy_from_user() don't matter
in this case.  Is this correct for all arch's?  I don't see this
behavior documented anywhere.

urs
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