From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Morton <akpm@linux-foundation.org>
Subject: qstr abuse in git-cifs
Date: Mon, 5 Nov 2007 23:28:43 -0800
Message-ID: <20071105232843.6c34313e.akpm@linux-foundation.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: linux-fsdevel@vger.kernel.org
To: Steven French <sfrench@us.ibm.com>
Return-path: <linux-fsdevel-owner@vger.kernel.org>
Received: from smtp2.linux-foundation.org ([207.189.120.14]:48377 "EHLO
	smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK)
	by vger.kernel.org with ESMTP id S1750741AbXKFHeF (ORCPT
	<rfc822;linux-fsdevel@vger.kernel.org>);
	Tue, 6 Nov 2007 02:34:05 -0500
Sender: linux-fsdevel-owner@vger.kernel.org
List-Id: linux-fsdevel.vger.kernel.org


static int cifs_ci_compare(struct dentry *dentry, struct qstr *a,
                           struct qstr *b)
{
        struct nls_table *codepage = CIFS_SB(dentry->d_inode->i_sb)->local_nls;

        if ((a->len == b->len) &&
            (nls_strnicmp(codepage, a->name, b->name, a->len) == 0)) {
                /*
                 * To preserve case, don't let an existing negative dentry's
                 * case take precedence.  If a is not a negative dentry, this
                 * should have no side effects
                 */
                memcpy(a->name, b->name, a->len);
                return 0;
        }
        return 1;
}

produces

fs/cifs/dir.c: In function 'cifs_ci_compare':
fs/cifs/dir.c:596: warning: passing argument 1 of '__constant_memcpy' discards qualifiers from pointer target type
fs/cifs/dir.c:596: warning: passing argument 1 of '__memcpy' discards qualifiers from pointer target type

I suspect that bad things are happening in there.

It's strange for a "comparison" function to go and alter one of the things
which it's comparing, too.