An issue was discovered in xfs_setattr_nonsize in fs/xfs/xfs_iops.c in the Linux kernel through 5.2.9. XFS partially wedges when a chgrp fails on account of being out of disk quota. xfs_setattr_nonsize is failing to unlock the ILOCK after the xfs_qm_vop_chown_reserve call fails. This is primarily a local DoS attack vector, but it might result as well in remote DoS if the XFS filesystem is exported for instance via NFS.
https://usn.ubuntu.com/4147-1/
https://usn.ubuntu.com/4144-1/
https://support.f5.com/csp/article/K32592426?utm_source=f5support&%3Butm_medium=RSS
https://security.netapp.com/advisory/ntap-20191004-0001/
https://lore.kernel.org/linux-xfs/20190823192433.GA8736%40eldamar.local
https://lore.kernel.org/linux-xfs/20190823035528.GH1037422%40magnolia/
https://lists.debian.org/debian-lts-announce/2019/09/msg00015.html
https://lists.debian.org/debian-lts-announce/2019/09/msg00014.html
https://github.com/torvalds/linux/commit/1fb254aa983bf190cfd685d40c64a480a9bafaee
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00066.html
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00064.html