omfs: refuse to mount if bitmap pointer is obviously wrong

If the free space bitmap pointer is corrupted such that it lies outside
of the number of blocks in the filesystem, print a message and fail the
mount so the user can fix it offline.

Signed-off-by: Bob Copeland <me@bobcopeland.com>

diff --git a/fs/omfs/inode.c b/fs/omfs/inode.c
index bd4bf753a63bf6f0257eeac13e59a21147d8a3b6..0af5d0af9f322b3fd1c64a8b7ac3f8bffb539644 100644 (file)
--- a/fs/omfs/inode.c
+++ b/fs/omfs/inode.c
@@ -509,6 +509,15 @@ static int omfs_fill_super(struct super_block *sb, void *data, int silent)
                goto out_brelse_bh2;
        }
 
+       if (sbi->s_bitmap_ino != ~0ULL &&
+           sbi->s_bitmap_ino > sbi->s_num_blocks) {
+               printk(KERN_ERR "omfs: free space bitmap location is corrupt "
+                       "(%llx, total blocks %llx)\n",
+                       (unsigned long long) sbi->s_bitmap_ino,
+                       (unsigned long long) sbi->s_num_blocks);
+               goto out_brelse_bh2;
+       }
+
        ret = omfs_get_imap(sb);
        if (ret)
                goto out_brelse_bh2;