Once you are in violation, you have two ways to fix it: stop publishing the software with the violation (and, optionally, publish a version without the violation instead) or give access to the source code. The main problem with accidental violation is that, with GPLv2, you need to have an agreement with the copyright holder to unterminate your license. With GPLv3, you have a grace period and major copyright holders (like Redhat) told they would also use a grace period for GPLv2.