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, 74 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/ts2020.h b/drivers/media/dvb-frontends/ts2020.h
new file mode 100644
index 000000000..84c2dc8c3
--- /dev/null
+++ b/drivers/media/dvb-frontends/ts2020.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+    Montage Technology TS2020 - Silicon Tuner driver
+    Copyright (C) 2009-2012 Konstantin Dimitrov <kosio.dimitrov@gmail.com>
+
+    Copyright (C) 2009-2012 TurboSight.com
+
+ */
+
+#ifndef TS2020_H
+#define TS2020_H
+
+#include <linux/dvb/frontend.h>
+
+struct ts2020_config {
+	u8 tuner_address;
+	u32 frequency_div;
+
+	/*
+	 * RF loop-through
+	 */
+	bool loop_through:1;
+
+	/*
+	 * clock output
+	 */
+#define TS2020_CLK_OUT_DISABLED        0
+#define TS2020_CLK_OUT_ENABLED         1
+#define TS2020_CLK_OUT_ENABLED_XTALOUT 2
+	u8 clk_out:2;
+
+	/*
+	 * clock output divider
+	 * 1 - 31
+	 */
+	u8 clk_out_div:5;
+
+	/* Set to true to suppress stat polling */
+	bool dont_poll:1;
+
+	/*
+	 * pointer to DVB frontend
+	 */
+	struct dvb_frontend *fe;
+
+	/*
+	 * driver private, do not set value
+	 */
+	u8 attach_in_use:1;
+
+	/* Operation to be called by the ts2020 driver to get the value of the
+	 * AGC PWM tuner input as theoretically output by the demodulator.
+	 */
+	int (*get_agc_pwm)(struct dvb_frontend *fe, u8 *_agc_pwm);
+};
+
+/* Do not add new ts2020_attach() users! Use I2C bindings instead. */
+#if IS_REACHABLE(CONFIG_DVB_TS2020)
+extern struct dvb_frontend *ts2020_attach(
+	struct dvb_frontend *fe,
+	const struct ts2020_config *config,
+	struct i2c_adapter *i2c);
+#else
+static inline struct dvb_frontend *ts2020_attach(
+	struct dvb_frontend *fe,
+	const struct ts2020_config *config,
+	struct i2c_adapter *i2c)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+#endif
+
+#endif /* TS2020_H */