BugZilla is a commonly used bug report management system.

DRI and Mesa bugs should be submitted at freedesktop.org's Bugzilla. Bug reports submitted in this fashion will be automatically forwarded to the dri-devel mailing list. Please submit all new bugs here.

There are also older bug databases for DRI at xfree86.org and sourceforge.net, but these are deprecated, and should not be used for submitting new bugs.