Yes, you have to do the kernel flash in Odin to downgrade the kernel to one that hasn't been patched to block the exploit. Once you are rooted and update the su binary, it is actually recommended that you flash back to the kernel that came with the phone to ensure that everything continues to work right. Doing so shouldn't affect your root unless you fail to update the su binary.
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Current Devices: Nexus 5, Asus TF700, Google Glass, (2013) LTE Nexus 7, Logitech Revue, Chromecast
Retired: Samsung Fascinate, Droid Charge, Galaxy Nexus, (2012) WiFi Nexus 7, Nexus 4