[src/trunk]: src/sys In layer_lookup(), clear *vpp before returning EROFS, as...

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

details:   https://anonhg.NetBSD.org/src/rev/24bb1fcdc7d3
branches:  trunk
changeset: 781959:24bb1fcdc7d3
user:      dholland <dholland%NetBSD.org@localhost>
date:      Wed Oct 10 06:55:25 2012 +0000

description:
In layer_lookup(), clear *vpp before returning EROFS, as otherwise a
stale value can be returned and this causes a diagnostic panic in
namei.

In relookup(), clear *vpp before calling VOP_LOOKUP, as is done in
lookup_once(), as an additional precautionary measure.

(in theory both of these fixes are not required together)

Should fix PR 47040.

diffstat:

 sys/kern/vfs_lookup.c          |  5 +++--
 sys/miscfs/genfs/layer_vnops.c |  8 +++++---
 2 files changed, 8 insertions(+), 5 deletions(-)

diffs (56 lines):

diff -r 7096d036199c -r 24bb1fcdc7d3 sys/kern/vfs_lookup.c
--- a/sys/kern/vfs_lookup.c     Wed Oct 10 02:16:54 2012 +0000
+++ b/sys/kern/vfs_lookup.c     Wed Oct 10 06:55:25 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_lookup.c,v 1.194 2012/10/08 23:43:33 dholland Exp $        */
+/*     $NetBSD: vfs_lookup.c,v 1.195 2012/10/10 06:55:25 dholland Exp $        */
 
 /*
  * Copyright (c) 1982, 1986, 1989, 1993
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.194 2012/10/08 23:43:33 dholland Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.195 2012/10/10 06:55:25 dholland Exp $");
 
 #include "opt_magiclinks.h"
 
@@ -1708,6 +1708,7 @@
        /*
         * We now have a segment name to search for, and a directory to search.
         */
+       *vpp = NULL;
        cnp->cn_flags |= INRELOOKUP;
        error = VOP_LOOKUP(dvp, vpp, cnp);
        cnp->cn_flags &= ~INRELOOKUP;
diff -r 7096d036199c -r 24bb1fcdc7d3 sys/miscfs/genfs/layer_vnops.c
--- a/sys/miscfs/genfs/layer_vnops.c    Wed Oct 10 02:16:54 2012 +0000
+++ b/sys/miscfs/genfs/layer_vnops.c    Wed Oct 10 06:55:25 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: layer_vnops.c,v 1.50 2011/07/11 08:34:01 hannken Exp $ */
+/*     $NetBSD: layer_vnops.c,v 1.51 2012/10/10 06:55:25 dholland Exp $        */
 
 /*
  * Copyright (c) 1999 National Aeronautics & Space Administration
@@ -170,7 +170,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: layer_vnops.c,v 1.50 2011/07/11 08:34:01 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: layer_vnops.c,v 1.51 2012/10/10 06:55:25 dholland Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -353,8 +353,10 @@
        dvp = ap->a_dvp;
 
        if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
-           (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
+           (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
+               *ap->a_vpp = NULL;
                return EROFS;
+       }
 
        ldvp = LAYERVPTOLOWERVP(dvp);
        ap->a_dvp = ldvp;