[src/trunk]: src/sys/dev/wscons wsmux_getmux: do not increment nwsmux if allo...

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

details:   https://anonhg.NetBSD.org/src/rev/f26173e4e252
branches:  trunk
changeset: 773258:f26173e4e252
user:      rmind <rmind%NetBSD.org@localhost>
date:      Mon Jan 30 01:54:08 2012 +0000

description:
wsmux_getmux: do not increment nwsmux if allocation fails (might cause buffer
overflow).  Simplify slightly.

diffstat:

 sys/dev/wscons/wsmux.c |  25 +++++++++----------------
 1 files changed, 9 insertions(+), 16 deletions(-)

diffs (62 lines):

diff -r df7e19df6e0d -r f26173e4e252 sys/dev/wscons/wsmux.c
--- a/sys/dev/wscons/wsmux.c    Mon Jan 30 00:56:19 2012 +0000
+++ b/sys/dev/wscons/wsmux.c    Mon Jan 30 01:54:08 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: wsmux.c,v 1.53 2009/02/13 22:41:04 apb Exp $   */
+/*     $NetBSD: wsmux.c,v 1.54 2012/01/30 01:54:08 rmind Exp $ */
 
 /*
  * Copyright (c) 1998, 2005 The NetBSD Foundation, Inc.
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: wsmux.c,v 1.53 2009/02/13 22:41:04 apb Exp $");
+__KERNEL_RCSID(0, "$NetBSD: wsmux.c,v 1.54 2012/01/30 01:54:08 rmind Exp $");
 
 #include "opt_compat_netbsd.h"
 #include "opt_modular.h"
@@ -141,36 +141,29 @@
 }
 
 /* Keep track of all muxes that have been allocated */
+static struct wsmux_softc **wsmuxdevs = NULL;
 static int nwsmux = 0;
-static struct wsmux_softc **wsmuxdevs;
 
 /* Return mux n, create if necessary */
 struct wsmux_softc *
 wsmux_getmux(int n)
 {
        struct wsmux_softc *sc;
-       int i;
-       void *new;
 
        n = WSMUXDEV(n);        /* limit range */
 
        /* Make sure there is room for mux n in the table */
        if (n >= nwsmux) {
-               i = nwsmux;
-               nwsmux = n + 1;
-               if (i != 0)
-                       new = realloc(wsmuxdevs, nwsmux * sizeof (*wsmuxdevs),
-                                     M_DEVBUF, M_NOWAIT);
-               else
-                       new = malloc(nwsmux * sizeof (*wsmuxdevs),
-                                    M_DEVBUF, M_NOWAIT);
+               void *new;
+
+               new = realloc(wsmuxdevs, (n + 1) * sizeof(*wsmuxdevs),
+                   M_DEVBUF, M_ZERO | M_NOWAIT);
                if (new == NULL) {
                        printf("wsmux_getmux: no memory for mux %d\n", n);
-                       return (NULL);
+                       return NULL;
                }
                wsmuxdevs = new;
-               for (; i < nwsmux; i++)
-                       wsmuxdevs[i] = NULL;
+               nwsmux = n + 1;
        }
 
        sc = wsmuxdevs[n];