From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: copy_from_user From: Amol Kumar Lad In-Reply-To: <20021223012106.10392.qmail@web12301.mail.yahoo.com> References: <20021223012106.10392.qmail@web12301.mail.yahoo.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: 23 Dec 2002 10:02:18 -0500 Message-Id: <1040655739.4986.86.camel@amol.in.ishoni.com> Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org Return-Path: To: Ravi Cc: linux-mm@kvack.org List-ID: yeah..u are right... how stupid of me... I should have read whole function... I thought..aceess_ok should make such check... thanks Amol On Sun, 2002-12-22 at 20:21, Ravi wrote: > > --- Amol Kumar Lad wrote: > > > Suppose kernel tries to do copy_from_user from a pointer > > that does not have any mapping. i.e. not in any VMA (and not > in > > stack area too..). > > Now (for 1386) > > access_ok --> __range_ok > > Suppose the 'from' ptr is within range then how kernel is > > making sure that 'from' is invalid ?? > > The page fault handler will see that 'from' has no mapping and > > it will die.. > > I believe this is handled using the 'fixup' code in > __copy_user_zeroing(). > I don't understand the code well though, but I do know that it > works :) > > -Ravi. > > __________________________________________________ > Do you Yahoo!? > Yahoo! Mail Plus - Powerful. Affordable. Sign up now. > http://mailplus.yahoo.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/