selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/fs/xfs/xfs_acl.h b/fs/xfs/xfs_acl.h
new file mode 100644
index 000000000..bf7f96099
--- /dev/null
+++ b/fs/xfs/xfs_acl.h
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2001-2005 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ */
+#ifndef __XFS_ACL_H__
+#define __XFS_ACL_H__
+
+struct inode;
+struct posix_acl;
+
+#ifdef CONFIG_XFS_POSIX_ACL
+extern struct posix_acl *xfs_get_acl(struct inode *inode, int type, bool rcu);
+extern int xfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
+		       struct posix_acl *acl, int type);
+extern int __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type);
+void xfs_forget_acl(struct inode *inode, const char *name);
+#else
+#define xfs_get_acl NULL
+#define xfs_set_acl NULL
+static inline int __xfs_set_acl(struct inode *inode, struct posix_acl *acl,
+				int type)
+{
+	return 0;
+}
+static inline void xfs_forget_acl(struct inode *inode, const char *name)
+{
+}
+#endif /* CONFIG_XFS_POSIX_ACL */
+
+#endif	/* __XFS_ACL_H__ */