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, 26 insertions, 0 deletions

diff --git a/drivers/hid/hid-roccat-lua.h b/drivers/hid/hid-roccat-lua.h
new file mode 100644
index 000000000..1495e535e
--- /dev/null
+++ b/drivers/hid/hid-roccat-lua.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef __HID_ROCCAT_LUA_H
+#define __HID_ROCCAT_LUA_H
+
+/*
+ * Copyright (c) 2012 Stefan Achatz <erazor_de@users.sourceforge.net>
+ */
+
+/*
+ */
+
+#include <linux/types.h>
+
+enum {
+	LUA_SIZE_CONTROL = 8,
+};
+
+enum lua_commands {
+	LUA_COMMAND_CONTROL = 3,
+};
+
+struct lua_device {
+	struct mutex lua_lock;
+};
+
+#endif