ext4: Check for an valid i_mode when reading the inode from disk

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/inode.c

@@ -4394,7 +4394,8 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
 			inode->i_op = &ext4_symlink_inode_operations;
 			ext4_set_aops(inode);
 		}
-	} else {
+	} else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
+	      S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
 		inode->i_op = &ext4_special_inode_operations;
 		if (raw_inode->i_block[0])
 			init_special_inode(inode, inode->i_mode,
@@ -4402,6 +4403,13 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
 		else
 			init_special_inode(inode, inode->i_mode,
 			   new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
+	} else {
+		brelse(bh);
+		ret = -EIO;
+		ext4_error(inode->i_sb, __func__, 
+			   "bogus i_mode (%o) for inode=%lu",
+			   inode->i_mode, inode->i_ino);
+		goto bad_inode;
 	}
 	brelse(iloc.bh);
 	ext4_set_inode_flags(inode);