linux-kernel - Re: [PATCH] NOMMU: use copy_*_user_page() in access_process

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Message-ID: <16225.1259764594@redhat.com>
Date:	Wed, 02 Dec 2009 14:36:34 +0000
From:	David Howells <dhowells@...hat.com>
To:	Mike Frysinger <vapier@...too.org>
Cc:	dhowells@...hat.com, uclinux-dev@...inux.org,
	David McCullough <davidm@...pgear.com>,
	Greg Ungerer <gerg@...inux.org>,
	Paul Mundt <lethal@...ux-sh.org>, linux-kernel@...r.kernel.org,
	uclinux-dist-devel@...ckfin.uclinux.org,
	Jie Zhang <jie.zhang@...log.com>
Subject: Re: [PATCH] NOMMU: use copy_*_user_page() in access_process_vm()

Mike Frysinger <vapier@...too.org> wrote:

> -			len -= copy_to_user((void *) addr, buf, len);
> +			copy_to_user_page(vma, NULL, NULL,
> +					  (void *) addr, buf, len);
>  		else if (!write && vma->vm_flags & VM_MAYREAD)
> -			len -= copy_from_user(buf, (void *) addr, len);
> +			copy_from_user_page(vma, NULL, NULL,
> +					    buf, (void *) addr, len);

Hmmm...  With this, len isn't updated anymore, and so it alters the return
value of access_process_vm(), and means ptrace_readdata() won't now return
-EIO under some circumstances where it used to.  I'm not sure that matters,
though.

David
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