[src/trunk]: src/sys/kern CID-1427760: While overrun can't happen, make it ob...

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

details:   https://anonhg.NetBSD.org/src/rev/1d9d12234b38
branches:  trunk
changeset: 829196:1d9d12234b38
user:      christos <christos%NetBSD.org@localhost>
date:      Sun Jan 21 17:22:55 2018 +0000

description:
CID-1427760: While overrun can't happen, make it obvious that it can't

diffstat:

 sys/kern/core_elf32.c |  13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)

diffs (45 lines):

diff -r 18709023b103 -r 1d9d12234b38 sys/kern/core_elf32.c
--- a/sys/kern/core_elf32.c     Sun Jan 21 16:55:25 2018 +0000
+++ b/sys/kern/core_elf32.c     Sun Jan 21 17:22:55 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: core_elf32.c,v 1.55 2017/05/04 11:12:23 kamil Exp $    */
+/*     $NetBSD: core_elf32.c,v 1.56 2018/01/21 17:22:55 christos Exp $ */
 
 /*
  * Copyright (c) 2001 Wasabi Systems, Inc.
@@ -40,7 +40,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(1, "$NetBSD: core_elf32.c,v 1.55 2017/05/04 11:12:23 kamil Exp $");
+__KERNEL_RCSID(1, "$NetBSD: core_elf32.c,v 1.56 2018/01/21 17:22:55 christos Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_coredump.h"
@@ -505,12 +505,12 @@
         * All but the last buffer is full.
         */
        for (;;) {
-               copylen = min(len, sizeof nb->nb_data - ns->ns_offset);
+               copylen = min(len, sizeof(nb->nb_data) - ns->ns_offset);
                wp = nb->nb_data + ns->ns_offset;
                memcpy(wp, data, copylen);
                if (copylen == len)
                        break;
-               nb->nb_next = kmem_alloc(sizeof *nb->nb_next, KM_SLEEP);
+               nb->nb_next = kmem_alloc(sizeof(*nb->nb_next), KM_SLEEP);
                nb = nb->nb_next;
                ns->ns_last = nb;
                ns->ns_count++;
@@ -519,8 +519,9 @@
                data = (const unsigned char *)data + copylen;
        }
 
-       while (copylen & (ELFROUNDSIZE - 1))
-           wp[copylen++] = 0;
+       while ((copylen & (ELFROUNDSIZE - 1)) && 
+           wp + copylen < nb->nb_data + sizeof(nb->nb_data))
+               wp[copylen++] = 0;
 
        ns->ns_offset += copylen;
 }