From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f181.google.com ([209.85.192.181]:33566 "EHLO mail-pf0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751856AbdDEAMJ (ORCPT ); Tue, 4 Apr 2017 20:12:09 -0400 Received: by mail-pf0-f181.google.com with SMTP id s16so25545099pfs.0 for ; Tue, 04 Apr 2017 17:12:09 -0700 (PDT) Date: Tue, 4 Apr 2017 17:12:06 -0700 From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Trond Myklebust , Anna Schumaker , linux-nfs@vger.kernel.org Subject: [PATCH] NFS: Avoid cross-structure casting Message-ID: <20170405001206.GA58184@beast> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-nfs-owner@vger.kernel.org List-ID: When the call to nfs_devname() fails, the error path attempts to retain the error via the mnt variable, but this requires a cast across very different types (char * to struct vfsmount), which the upcoming structure layout randomization plugin flags as being potentially dangerous in the face of randomization. This is a false positive, but what this code actually wants to do is retain the error value, so this patch explicitly sets it, instead of using what seems to be an unexpected cast. Signed-off-by: Kees Cook --- fs/nfs/namespace.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c index 786f17580582..89f50bf12f52 100644 --- a/fs/nfs/namespace.c +++ b/fs/nfs/namespace.c @@ -259,9 +259,10 @@ struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh, if (page == NULL) goto out; devname = nfs_devname(dentry, page, PAGE_SIZE); - mnt = (struct vfsmount *)devname; - if (IS_ERR(devname)) + if (IS_ERR(devname)) { + mnt = ERR_PTR(PTR_ERR(devname)); goto free_page; + } mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata); free_page: free_page((unsigned long)page); -- 2.7.4 -- Kees Cook Pixel Security