[src/trunk]: src/sys/ufs/ffs Add a new function: ffs_superblock_validate(). A...

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

details:   https://anonhg.NetBSD.org/src/rev/df3092317465
branches:  trunk
changeset: 336110:df3092317465
user:      maxv <maxv%NetBSD.org@localhost>
date:      Fri Feb 13 15:52:29 2015 +0000

description:
Add a new function: ffs_superblock_validate(). And add a new check to
ensure fs_size!=0; otherwise the kernel panics with a division by zero.

diffstat:

 sys/ufs/ffs/ffs_vfsops.c |  32 +++++++++++++++++++++-----------
 1 files changed, 21 insertions(+), 11 deletions(-)

diffs (62 lines):

diff -r 3ea86a8b94dd -r df3092317465 sys/ufs/ffs/ffs_vfsops.c
--- a/sys/ufs/ffs/ffs_vfsops.c  Fri Feb 13 15:28:56 2015 +0000
+++ b/sys/ufs/ffs/ffs_vfsops.c  Fri Feb 13 15:52:29 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ffs_vfsops.c,v 1.306 2015/02/13 15:28:56 maxv Exp $    */
+/*     $NetBSD: ffs_vfsops.c,v 1.307 2015/02/13 15:52:29 maxv Exp $    */
 
 /*-
  * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -61,7 +61,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ffs_vfsops.c,v 1.306 2015/02/13 15:28:56 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ffs_vfsops.c,v 1.307 2015/02/13 15:52:29 maxv Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_ffs.h"
@@ -903,6 +903,24 @@
  */
 static const int sblock_try[] = SBLOCKSEARCH;
 
+
+static int
+ffs_superblock_validate(struct fs *fs, u_int32_t fs_sbsize, int32_t fs_bsize)
+{
+       /* Check the superblock size */
+       if (fs_sbsize > SBLOCKSIZE || fs_sbsize < sizeof(struct fs))
+               return 0;
+
+       /* Check the file system blocksize */
+       if (fs_bsize > MAXBSIZE)
+               return 0;
+
+       if (fs->fs_size == 0)
+               return 0;
+
+       return 1;
+}
+
 /*
  * Common code for mount and mountroot
  */
@@ -1037,17 +1055,9 @@
                if (fsblockloc != sblockloc)
                        continue;
 
-               /* Validate size of superblock */
-               if (fs_sbsize > SBLOCKSIZE || fs_sbsize < sizeof(struct fs))
+               if (!ffs_superblock_validate(fs, fs_sbsize, fs_bsize))
                        continue;
 
-               /* Check that we can handle the file system blocksize */
-               if (fs_bsize > MAXBSIZE) {
-                       printf("ffs_mountfs: block size (%d) > MAXBSIZE (%d)\n",
-                           fs_bsize, MAXBSIZE);
-                       continue;
-               }
-
                /* Ok seems to be a good superblock */
                break;
        }