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, 40 insertions, 0 deletions

diff --git a/fs/nfs/nfs4trace.c b/fs/nfs/nfs4trace.c
new file mode 100644
index 000000000..3fdc013f5
--- /dev/null
+++ b/fs/nfs/nfs4trace.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2013 Trond Myklebust <Trond.Myklebust@netapp.com>
+ */
+#include <uapi/linux/pr.h>
+#include <linux/blkdev.h>
+#include <linux/nfs_fs.h>
+#include "nfs4_fs.h"
+#include "internal.h"
+#include "nfs4session.h"
+#include "callback.h"
+#include "pnfs.h"
+
+#define CREATE_TRACE_POINTS
+#include "nfs4trace.h"
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(nfs4_pnfs_read);
+EXPORT_TRACEPOINT_SYMBOL_GPL(nfs4_pnfs_write);
+EXPORT_TRACEPOINT_SYMBOL_GPL(nfs4_pnfs_commit_ds);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(pnfs_mds_fallback_pg_init_read);
+EXPORT_TRACEPOINT_SYMBOL_GPL(pnfs_mds_fallback_pg_init_write);
+EXPORT_TRACEPOINT_SYMBOL_GPL(pnfs_mds_fallback_pg_get_mirror_count);
+EXPORT_TRACEPOINT_SYMBOL_GPL(pnfs_mds_fallback_read_done);
+EXPORT_TRACEPOINT_SYMBOL_GPL(pnfs_mds_fallback_write_done);
+EXPORT_TRACEPOINT_SYMBOL_GPL(pnfs_mds_fallback_read_pagelist);
+EXPORT_TRACEPOINT_SYMBOL_GPL(pnfs_mds_fallback_write_pagelist);
+EXPORT_TRACEPOINT_SYMBOL_GPL(pnfs_ds_connect);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(ff_layout_read_error);
+EXPORT_TRACEPOINT_SYMBOL_GPL(ff_layout_write_error);
+EXPORT_TRACEPOINT_SYMBOL_GPL(ff_layout_commit_error);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bl_ext_tree_prepare_commit);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bl_pr_key_reg);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bl_pr_key_reg_err);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bl_pr_key_unreg);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bl_pr_key_unreg_err);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(fl_getdevinfo);