Locked out of EC2 ubuntu instance because of /home perms

Following Tim's suggestion:

I clicked Launch Instance to create a new instance. I just took whatever the first AMI was listed (some Amazon version of Linux) and created it with defaults, using a keypair I had already on hand.

I then clicked on Volumes and detached the EBS volume from my hosed machine. This took about 30 secs. Then I selected Attach Volume and I attached it to the new instance as /dev/sdf. Then I sshed into the new instance.

In the new instance I typed

$ sudo mkdir /caribou
$ sudo mount /dev/sdf1 /caribou
$ cd /caribou
$ sudo chmod 755 home

That repaired the /home dir permissions.

I then went back to the EC2 console, detached the EBS volume from the Amazon instance and re-attached it to my original Ubuntu instance as /dev/sda1. Then I started the old instance and logged in, with everything fixed.

Took 30 mins including time to figure out all of the above. Thanks to Tim.