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, 53 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/ix2505v.h b/drivers/media/dvb-frontends/ix2505v.h
new file mode 100644
index 000000000..175569131
--- /dev/null
+++ b/drivers/media/dvb-frontends/ix2505v.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Driver for Sharp IX2505V (marked B0017) DVB-S silicon tuner
+ *
+ * Copyright (C) 2010 Malcolm Priestley
+ */
+
+#ifndef DVB_IX2505V_H
+#define DVB_IX2505V_H
+
+#include <linux/i2c.h>
+#include <media/dvb_frontend.h>
+
+/**
+ * struct ix2505v_config - ix2505 attachment configuration
+ *
+ * @tuner_address: tuner address
+ * @tuner_gain: Baseband AMP gain control 0/1=0dB(default) 2=-2bB 3=-4dB
+ * @tuner_chargepump: Charge pump output +/- 0=120 1=260 2=555 3=1200(default)
+ * @min_delay_ms: delay after tune
+ * @tuner_write_only: disables reads
+ */
+struct ix2505v_config {
+	u8 tuner_address;
+	u8 tuner_gain;
+	u8 tuner_chargepump;
+	int min_delay_ms;
+	u8 tuner_write_only;
+
+};
+
+#if IS_REACHABLE(CONFIG_DVB_IX2505V)
+/**
+ * ix2505v_attach - Attach a ix2505v tuner to the supplied frontend structure.
+ *
+ * @fe: Frontend to attach to.
+ * @config: pointer to &struct ix2505v_config
+ * @i2c: pointer to &struct i2c_adapter.
+ *
+ * return: FE pointer on success, NULL on failure.
+ */
+extern struct dvb_frontend *ix2505v_attach(struct dvb_frontend *fe,
+	const struct ix2505v_config *config, struct i2c_adapter *i2c);
+#else
+static inline struct dvb_frontend *ix2505v_attach(struct dvb_frontend *fe,
+	const struct ix2505v_config *config, struct i2c_adapter *i2c)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+#endif
+
+#endif /* DVB_IX2505V_H */