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, 49 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/m88rs2000.h b/drivers/media/dvb-frontends/m88rs2000.h
new file mode 100644
index 000000000..3a141b02d
--- /dev/null
+++ b/drivers/media/dvb-frontends/m88rs2000.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+	Driver for M88RS2000 demodulator
+
+
+*/
+
+#ifndef M88RS2000_H
+#define M88RS2000_H
+
+#include <linux/dvb/frontend.h>
+#include <media/dvb_frontend.h>
+
+struct m88rs2000_config {
+	/* Demodulator i2c address */
+	u8 demod_addr;
+
+	u8 *inittab;
+
+	/* minimum delay before retuning */
+	int min_delay_ms;
+
+	int (*set_ts_params)(struct dvb_frontend *, int);
+};
+
+enum {
+	CALL_IS_SET_FRONTEND = 0x0,
+	CALL_IS_READ,
+};
+
+#if IS_REACHABLE(CONFIG_DVB_M88RS2000)
+extern struct dvb_frontend *m88rs2000_attach(
+	const struct m88rs2000_config *config, struct i2c_adapter *i2c);
+#else
+static inline struct dvb_frontend *m88rs2000_attach(
+	const struct m88rs2000_config *config, struct i2c_adapter *i2c)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+#endif /* CONFIG_DVB_M88RS2000 */
+
+#define RS2000_FE_CRYSTAL_KHZ 27000
+
+enum {
+	DEMOD_WRITE = 0x1,
+	WRITE_DELAY = 0x10,
+};
+#endif /* M88RS2000_H */