From 4a33821236f2ef3af0081e8a5eec1301cbed3125 Mon Sep 17 00:00:00 2001 From: Dave Chinner <dchinner@redhat.com> Date: Thu, 23 Jun 2011 01:35:01 +0000 Subject: [PATCH] xfs: prevent bogus assert when trying to remove non-existent attribute If the attribute fork on an inode is in btree format and has multiple levels (i.e node format rather than leaf format), then a lookup failure will trigger an assert failure in xfs_da_path_shift if the flag XFS_DA_OP_OKNOENT is not set. This flag is used to indicate to the directory btree code that not finding an entry is not a fatal error. In the case of doing a lookup for a directory name removal, this is valid as a user cannot insert an arbitrary name to remove from the directory btree. However, in the case of the attribute tree, a user has direct control over the attribute name and can ask for any random name to be removed without any validation. In this case, fsstress is asking for a non-existent user.selinux attribute to be removed, and that is causing xfs_da_path_shift() to fall off the bottom of the tree where it asserts that a lookup failure is allowed. Because the flag is not set, we die a horrible death on a debug enable kernel. Prevent this assert from firing on attribute removes by adding the op_flag XFS_DA_OP_OKNOENT to atribute removal operations. Discovered when testing on a SELinux enabled system by fsstress in test 070 by trying to remove a non-existent user.selinux attribute. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com> --- fs/xfs/xfs_attr.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/xfs/xfs_attr.c b/fs/xfs/xfs_attr.c index c86375378810..01d2072fb6d4 100644 --- a/fs/xfs/xfs_attr.c +++ b/fs/xfs/xfs_attr.c @@ -489,6 +489,13 @@ xfs_attr_remove_int(xfs_inode_t *dp, struct xfs_name *name, int flags) args.total = 0; args.whichfork = XFS_ATTR_FORK; + /* + * we have no control over the attribute names that userspace passes us + * to remove, so we have to allow the name lookup prior to attribute + * removal to fail. + */ + args.op_flags = XFS_DA_OP_OKNOENT; + /* * Attach the dquots to the inode. */ -- 2.20.1