Public bug reported: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512
affects ubuntu/cron A user permitted to install a crontab can substantially delay the central cron daemon by submitting many environment assignments. The crontab command accepts them quickly, while the daemon repeatedly scans and reallocates its growing environment during load_user(). Loading grows approximately quadratically for many distinct long names with common prefixes. Isolated measurements on Ubuntu's packaged source: 1,000 assignments parsed in 0.23 s; 8,000 in 14.35 s. A 9.28 MB crontab was accepted by crontab(1) in about 0.2 s, but the daemon's database-loading path took about 22 s. Editing and reloading caused a similar delay. A practical worst case and out-of-memory daemon failure have not been established; no privilege escalation was demonstrated. Debian report with an issue-specific patch and regression tests: https://bugs.debian.org/1152897 We also prepared and tested a private local Ubuntu 3.0pl1-209ubuntu1+daybreak1 source package preserving Ubuntu's PATH behavior. The fix indexes environment names, grows the ordered vector geometrically, and adds 16 MiB file and environment-accounting budgets. Ubuntu focused and root-only tests passed in a disposable container. The Debian patched source built in a disposable trixie container and passed all 13 existing Debian integration tests. Ubuntu and Debian Security Teams recommended public bug reports for these findings. Please consider a fix in Ubuntu, including supported-release backports as appropriate. Brett Sutton -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQT9urELYHGjhO/7gF+TZqY73ysXxAUCauk+/AAKCRCTZqY73ysX xHBnAPwMb5K2ji0twgp26m0EhX0X08pfb71WOqQrL0JZNmadBwD/SUGbKNgsO4tx G+mXpk6mAheSWs9ItZYO0w9sTJH2oA0= =gEM4 -----END PGP SIGNATURE----- ** Affects: cron (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2172792 Title: cron daemon can stall while loading environment-heavy crontabs To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/cron/+bug/2172792/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
