[src/trunk]: src/sys/nfs Return an error if NFSPROC_LOOKUP returns the file h...

[hannken <hannken%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b9cddbd6be7a
branches:  trunk
changeset: 813161:b9cddbd6be7a
user:      hannken <hannken%NetBSD.org@localhost>
date:      Tue Jan 19 10:56:59 2016 +0000

description:
Return an error if NFSPROC_LOOKUP returns the file handle of the current
directory.  Treating it as DOT lookup would put garbage into the name
cache and could panic on future lookups.

Seen with ZFS file system exported from OmniOS, an OpenSolaris derivative.

Fixes PR kern/50664 "cd .." over NFS/ZFS can panic kernel

diffstat:

 sys/nfs/nfs_vnops.c |  17 +++++------------
 1 files changed, 5 insertions(+), 12 deletions(-)

diffs (40 lines):

diff -r 62b7e025c873 -r b9cddbd6be7a sys/nfs/nfs_vnops.c
--- a/sys/nfs/nfs_vnops.c       Tue Jan 19 10:11:02 2016 +0000
+++ b/sys/nfs/nfs_vnops.c       Tue Jan 19 10:56:59 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nfs_vnops.c,v 1.308 2015/05/14 17:35:54 chs Exp $      */
+/*     $NetBSD: nfs_vnops.c,v 1.309 2016/01/19 10:56:59 hannken Exp $  */
 
 /*
  * Copyright (c) 1989, 1993
@@ -39,7 +39,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nfs_vnops.c,v 1.308 2015/05/14 17:35:54 chs Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nfs_vnops.c,v 1.309 2016/01/19 10:56:59 hannken Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_nfs.h"
@@ -954,18 +954,11 @@
 
        if (NFS_CMPFH(np, fhp, fhsize)) {
                /*
-                * as we handle "." lookup locally, this should be
+                * As we handle "." lookup locally, this is
                 * a broken server.
                 */
-               vref(dvp);
-               newvp = dvp;
-#ifndef NFS_V2_ONLY
-               if (v3) {
-                       nfsm_postop_attr(newvp, attrflag, 0);
-                       nfsm_postop_attr(dvp, attrflag, 0);
-               } else
-#endif
-                       nfsm_loadattr(newvp, (struct vattr *)0, 0);
+               m_freem(mrep);
+               return EBADRPC;
        } else if (flags & ISDOTDOT) {
                /*
                 * ".." lookup