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, 23 insertions, 0 deletions

diff --git a/sound/usb/6fire/firmware.h b/sound/usb/6fire/firmware.h
new file mode 100644
index 000000000..c29ed9cd2
--- /dev/null
+++ b/sound/usb/6fire/firmware.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Linux driver for TerraTec DMX 6Fire USB
+ *
+ * Author: Torsten Schenk
+ * Created: Jan 01, 2011
+ * Copyright:	(C) Torsten Schenk
+ */
+
+#ifndef USB6FIRE_FIRMWARE_H
+#define USB6FIRE_FIRMWARE_H
+
+#include "common.h"
+
+enum /* firmware state of device */
+{
+	FW_READY = 0,
+	FW_NOT_READY = 1
+};
+
+int usb6fire_fw_init(struct usb_interface *intf);
+#endif /* USB6FIRE_FIRMWARE_H */
+