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, 32 insertions, 0 deletions

diff --git a/fs/dlm/recover.h b/fs/dlm/recover.h
new file mode 100644
index 000000000..ec6989646
--- /dev/null
+++ b/fs/dlm/recover.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
+**  Copyright (C) 2004-2005 Red Hat, Inc.  All rights reserved.
+**
+**
+*******************************************************************************
+******************************************************************************/
+
+#ifndef __RECOVER_DOT_H__
+#define __RECOVER_DOT_H__
+
+int dlm_wait_function(struct dlm_ls *ls, int (*testfn) (struct dlm_ls *ls));
+uint32_t dlm_recover_status(struct dlm_ls *ls);
+void dlm_set_recover_status(struct dlm_ls *ls, uint32_t status);
+int dlm_recover_members_wait(struct dlm_ls *ls, uint64_t seq);
+int dlm_recover_directory_wait(struct dlm_ls *ls, uint64_t seq);
+int dlm_recover_locks_wait(struct dlm_ls *ls, uint64_t seq);
+int dlm_recover_done_wait(struct dlm_ls *ls, uint64_t seq);
+int dlm_recover_masters(struct dlm_ls *ls, uint64_t seq,
+			const struct list_head *root_list);
+int dlm_recover_master_reply(struct dlm_ls *ls, const struct dlm_rcom *rc);
+int dlm_recover_locks(struct dlm_ls *ls, uint64_t seq,
+		      const struct list_head *root_list);
+void dlm_recovered_lock(struct dlm_rsb *r);
+void dlm_clear_inactive(struct dlm_ls *ls);
+void dlm_recover_rsbs(struct dlm_ls *ls, const struct list_head *root_list);
+
+#endif				/* __RECOVER_DOT_H__ */
+