6d200bdc01
This series fixes a use-after-free bug that syzbot uncovered. The UAF itself is a result of a race condition between getxattr and removexattr because callers to getxattr do not necessarily take any sort of locks before calling into the filesystem. Although the race condition itself can be fixed through clever use of a memory barrier, further consideration of the use cases of extended attributes shows that most files always have at least one attribute, so we might as well make them permanent. v2: Minor tweaks suggested by Dave, and convert some more macros to helper functions. Signed-off-by: Darrick J. Wong <djwong@kernel.org> -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEUzaAxoMeQq6m2jMV+H93GTRKtOsFAmLQRsAACgkQ+H93GTRK tOseOw/+JdSH2MU2xx+XoE5M/fStzGpw0UsoOqDo8kUPKDt3z12NwuczlL4OAiuw XFrN/1IAnxBsTD9YxFYbqoCPNi/VR81ajfWV7JqD2B1Joj0aATsxGDdNUYJnxCdU HMlMqP5o77XvArwkxFbgxYi7UGdAeNwXxqUJcJ8FopQo2lb8+SG6XzpLgGKnyrKT FRNKXNObplhtzOs/Bv8qYAxJulmmjkktFJXhK2OAUJlIDjFwFY9Wo2T4QuOVe9w+ NXFOYyu0BqWLpDZQkYKWoCnF0GNsUavS8DP6zZYW3qJ6mX/f1jmtfbOLAkHNhlh8 uHy/3k3SeQhKztTqM28sPioe6mdj2xocorDCCVBgGXgWxVF6aWeM/PS4tMTWN/Bg TWd1egERpeVC0Ymkm0LTCIDNuLqxsknK1G6sxXhwrQ8cw/70Gl08ePwgdyZ6hpD9 Q61iJQofcI7MJX189a2VSbbHRzFnZIA+uVK4oyhmdEkQVKTHgmzwHVP660oAv9bD Y5hqkWEoyKTaaCsOWRAPVXG3k03lq+TNcaGggZgwFx11Gw4oMEx5hMUztoP54xX4 aEXb1HWcCmMxy8llnFY/82baW98ucwl8FwWF1qhNIPT40mYx9IobDmvkCtNrAoOC 41U7O8CxxPlt7XKxoRhafQOAhzp0ZzuhCdbaFIUENV7pTAJtq5Q= =W3Ad -----END PGP SIGNATURE----- Merge tag 'make-attr-fork-permanent-5.20_2022-07-14' of git://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-5.20-mergeB xfs: make attr forks permanent This series fixes a use-after-free bug that syzbot uncovered. The UAF itself is a result of a race condition between getxattr and removexattr because callers to getxattr do not necessarily take any sort of locks before calling into the filesystem. Although the race condition itself can be fixed through clever use of a memory barrier, further consideration of the use cases of extended attributes shows that most files always have at least one attribute, so we might as well make them permanent. v2: Minor tweaks suggested by Dave, and convert some more macros to helper functions. Signed-off-by: Darrick J. Wong <djwong@kernel.org> * tag 'make-attr-fork-permanent-5.20_2022-07-14' of git://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux: xfs: replace inode fork size macros with functions xfs: replace XFS_IFORK_Q with a proper predicate function xfs: use XFS_IFORK_Q to determine the presence of an xattr fork xfs: make inode attribute forks a permanent part of struct xfs_inode xfs: convert XFS_IFORK_PTR to a static inline helper