[src/trunk]: src/usr.sbin/dumplfs If the number of inodes per block is zero, ...

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

details:   https://anonhg.NetBSD.org/src/rev/eddaedbf235d
branches:  trunk
changeset: 347071:eddaedbf235d
user:      dholland <dholland%NetBSD.org@localhost>
date:      Fri Aug 12 08:22:13 2016 +0000

description:
If the number of inodes per block is zero, bail instead of using
uninitialized stack trash as a dinode pointer. Fixes PR 51409 where
"dumplfs /dev/zero" receives SIGSEGV.

diffstat:

 usr.sbin/dumplfs/dumplfs.c |  11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diffs (38 lines):

diff -r 2f36c9b7d4d7 -r eddaedbf235d usr.sbin/dumplfs/dumplfs.c
--- a/usr.sbin/dumplfs/dumplfs.c        Fri Aug 12 03:17:41 2016 +0000
+++ b/usr.sbin/dumplfs/dumplfs.c        Fri Aug 12 08:22:13 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: dumplfs.c,v 1.62 2016/06/15 14:07:54 riastradh Exp $   */
+/*     $NetBSD: dumplfs.c,v 1.63 2016/08/12 08:22:13 dholland Exp $    */
 
 /*-
  * Copyright (c) 1991, 1993
@@ -40,7 +40,7 @@
 #if 0
 static char sccsid[] = "@(#)dumplfs.c  8.5 (Berkeley) 5/24/95";
 #else
-__RCSID("$NetBSD: dumplfs.c,v 1.62 2016/06/15 14:07:54 riastradh Exp $");
+__RCSID("$NetBSD: dumplfs.c,v 1.63 2016/08/12 08:22:13 dholland Exp $");
 #endif
 #endif /* not lint */
 
@@ -336,12 +336,19 @@
                err(1, "malloc");
        get(fd, fsbtobyte(lfsp, addr), dpage, psize);
 
+       dip = NULL;
        for (i = LFS_INOPB(lfsp); i-- > 0; ) {
                dip = DINO_IN_BLOCK(lfsp, dpage, i);
                if (lfs_dino_getinumber(lfsp, dip) == LFS_IFILE_INUM)
                        break;
        }
 
+       /* just in case */
+       if (dip == NULL) {
+               warnx("this volume apparently has zero inodes per block");
+               return;
+       }
+
        if (lfs_dino_getinumber(lfsp, dip) != LFS_IFILE_INUM) {
                warnx("unable to locate ifile inode at disk address 0x%jx",
                     (uintmax_t)addr);