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, 43 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/sp2.h b/drivers/media/dvb-frontends/sp2.h
new file mode 100644
index 000000000..b5ace0d76
--- /dev/null
+++ b/drivers/media/dvb-frontends/sp2.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * CIMaX SP2/HF CI driver
+ *
+ * Copyright (C) 2014 Olli Salonen <olli.salonen@iki.fi>
+ */
+
+#ifndef SP2_H
+#define SP2_H
+
+#include <media/dvb_ca_en50221.h>
+
+/*
+ * I2C address
+ * 0x40 (port 0)
+ * 0x41 (port 1)
+ */
+struct sp2_config {
+	/* dvb_adapter to attach the ci to */
+	struct dvb_adapter *dvb_adap;
+
+	/* function ci_control handles the device specific ci ops */
+	void *ci_control;
+
+	/* priv is passed back to function ci_control */
+	void *priv;
+};
+
+extern int sp2_ci_read_attribute_mem(struct dvb_ca_en50221 *en50221,
+					int slot, int addr);
+extern int sp2_ci_write_attribute_mem(struct dvb_ca_en50221 *en50221,
+					int slot, int addr, u8 data);
+extern int sp2_ci_read_cam_control(struct dvb_ca_en50221 *en50221,
+					int slot, u8 addr);
+extern int sp2_ci_write_cam_control(struct dvb_ca_en50221 *en50221,
+					int slot, u8 addr, u8 data);
+extern int sp2_ci_slot_reset(struct dvb_ca_en50221 *en50221, int slot);
+extern int sp2_ci_slot_shutdown(struct dvb_ca_en50221 *en50221, int slot);
+extern int sp2_ci_slot_ts_enable(struct dvb_ca_en50221 *en50221, int slot);
+extern int sp2_ci_poll_slot_status(struct dvb_ca_en50221 *en50221,
+					int slot, int open);
+
+#endif