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, 19 insertions, 0 deletions

diff --git a/fs/nfs/nfs40.h b/fs/nfs/nfs40.h
new file mode 100644
index 000000000..ee09aac73
--- /dev/null
+++ b/fs/nfs/nfs40.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_FS_NFS_NFS4_0_H
+#define __LINUX_FS_NFS_NFS4_0_H
+
+
+/* nfs40client.c */
+void nfs40_shutdown_client(struct nfs_client *);
+int nfs40_init_client(struct nfs_client *);
+void nfs40_handle_cb_pathdown(struct nfs_client *clp);
+
+/* nfs40proc.c */
+extern const struct nfs4_minor_version_ops nfs_v4_0_minor_ops;
+
+/* nfs40state.c */
+int nfs40_discover_server_trunking(struct nfs_client *clp,
+				   struct nfs_client **result,
+				   const struct cred *cred);
+
+#endif /* __LINUX_FS_NFS_NFS4_0_H */