Does Yum update running process?

Question

I am running Fedora 20 on my desktop. When I saw the advisory about the vulnerability in bash, I checked my system out and turns out, it was vulnerable. Today, I updated my system and a new version of bash was installed. I was expecting to restart bash for the changes to take effect. But to my surprise, the update process somehow fixed running copy of bash.

How?

Log: shows 2 invocations of the same command. Between the two, upgraded the system from a different xterm window.

bash$ env x='() { :;}; echo vulnerable' bash -c "echo This is a test" vulnerable This is a test bash$ env x='() { :;}; echo vulnerable' bash -c "echo This is a test" bash: warning: x: ignoring function definition attempt bash: error importing function definition for `x'

Answer 1

If you split the command into two it's clearer:

env x='() { :;}; echo vulnerable'
bash -c "echo This is a test"

You're running a new instance of bash when checking for the bug, so it's using the updated code. You should make sure to restart all your shells to ensure that you're safe.