omfs: sanity check cluster size

A corrupt filesystem could have a bad cluster size; this could result in
the filesystem allocating too much space for files if too large, or
getting stuck in omfs_allocate_block if too small.  The proper range is
1-8 blocks.

Reported-by: Eric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: Bob Copeland <me@bobcopeland.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/omfs/inode.c b/fs/omfs/inode.c
index 0af5d0af9f32..579d33fedddd 100644
--- a/fs/omfs/inode.c
+++ b/fs/omfs/inode.c
@@ -517,6 +517,12 @@ static int omfs_fill_super(struct super_block *sb, void *data, int silent)
                         (unsigned long long) sbi->s_num_blocks);
                 goto out_brelse_bh2;
         }
+        if (sbi->s_clustersize < 1 ||
+            sbi->s_clustersize > OMFS_MAX_CLUSTER_SIZE) {
+                printk(KERN_ERR "omfs: cluster size out of range (%d)",
+                        sbi->s_clustersize);
+                goto out_brelse_bh2;
+        }
 
         ret = omfs_get_imap(sb);
         if (ret)