[src/trunk]: src/sys/miscfs/fdesc Make sure fdesc_lookup() never returns VNON...

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

details:   https://anonhg.NetBSD.org/src/rev/a012418e1098
branches:  trunk
changeset: 378965:a012418e1098
user:      hannken <hannken%NetBSD.org@localhost>
date:      Sat May 01 15:08:14 2021 +0000

description:
Make sure fdesc_lookup() never returns VNON vnodes.

Should fix PR kern/56130 (fdescfs create nodes with wrong major number)

diffstat:

 sys/miscfs/fdesc/fdesc_vnops.c |  19 +++++++++++++++----
 1 files changed, 15 insertions(+), 4 deletions(-)

diffs (41 lines):

diff -r 3662731a5cab -r a012418e1098 sys/miscfs/fdesc/fdesc_vnops.c
--- a/sys/miscfs/fdesc/fdesc_vnops.c    Sat May 01 14:00:57 2021 +0000
+++ b/sys/miscfs/fdesc/fdesc_vnops.c    Sat May 01 15:08:14 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: fdesc_vnops.c,v 1.134 2020/06/27 17:29:19 christos Exp $       */
+/*     $NetBSD: fdesc_vnops.c,v 1.135 2021/05/01 15:08:14 hannken Exp $        */
 
 /*
  * Copyright (c) 1992, 1993
@@ -41,7 +41,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: fdesc_vnops.c,v 1.134 2020/06/27 17:29:19 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: fdesc_vnops.c,v 1.135 2021/05/01 15:08:14 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -295,9 +295,20 @@ bad:
 good:
        KASSERT(ix != -1);
        error = vcache_get(dvp->v_mount, &ix, sizeof(ix), vpp);
-       if (error == 0 && ix == FD_CTTY)
+       if (error)
+               return error;
+
+       /*
+        * Prevent returning VNON nodes.
+        * Operation fdesc_inactive() will reset the type to VNON.
+        */
+       if (ix == FD_CTTY)
                (*vpp)->v_type = VCHR;
-       return error;
+       else if (ix >= FD_DESC)
+               (*vpp)->v_type = VREG;
+       KASSERT((*vpp)->v_type != VNON);
+
+       return 0;
 }
 
 int