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, 51 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/si2168.h b/drivers/media/dvb-frontends/si2168.h
new file mode 100644
index 000000000..ecd21adf8
--- /dev/null
+++ b/drivers/media/dvb-frontends/si2168.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Silicon Labs Si2168 DVB-T/T2/C demodulator driver
+ *
+ * Copyright (C) 2014 Antti Palosaari <crope@iki.fi>
+ */
+
+#ifndef SI2168_H
+#define SI2168_H
+
+#include <linux/dvb/frontend.h>
+/**
+ * struct si2168_config - configuration parameters for si2168
+ *
+ * @fe:
+ *	frontend returned by driver
+ * @i2c_adapter:
+ *	tuner I2C adapter returned by driver
+ * @ts_mode:
+ *	Transport Stream mode. Can be:
+ *	- %SI2168_TS_PARALLEL
+ *	- %SI2168_TS_SERIAL
+ *	- %SI2168_TS_TRISTATE
+ *	- %SI2168_TS_CLK_MANUAL
+ * @ts_clock_inv:
+ *	TS clock inverted
+ * @ts_clock_gapped:
+ *	TS clock gapped
+ * @spectral_inversion:
+ *	Inverted spectrum
+ *
+ * Note:
+ *	The I2C address of this demod is 0x64.
+ */
+struct si2168_config {
+	struct dvb_frontend **fe;
+	struct i2c_adapter **i2c_adapter;
+
+#define SI2168_TS_PARALLEL	0x06
+#define SI2168_TS_SERIAL	0x03
+#define SI2168_TS_TRISTATE	0x00
+#define SI2168_TS_CLK_MANUAL	0x20
+	u8 ts_mode;
+
+	/* Flags */
+	unsigned int ts_clock_inv:1;
+	unsigned int ts_clock_gapped:1;
+	unsigned int spectral_inversion:1;
+};
+
+#endif