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, 50 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/mn88472.h b/drivers/media/dvb-frontends/mn88472.h
new file mode 100644
index 000000000..e4f217747
--- /dev/null
+++ b/drivers/media/dvb-frontends/mn88472.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Panasonic MN88472 DVB-T/T2/C demodulator driver
+ *
+ * Copyright (C) 2013 Antti Palosaari <crope@iki.fi>
+ */
+
+#ifndef MN88472_H
+#define MN88472_H
+
+#include <linux/dvb/frontend.h>
+
+/* Define old names for backward compatibility */
+#define VARIABLE_TS_CLOCK   MN88472_TS_CLK_VARIABLE
+#define FIXED_TS_CLOCK      MN88472_TS_CLK_FIXED
+#define SERIAL_TS_MODE      MN88472_TS_MODE_SERIAL
+#define PARALLEL_TS_MODE    MN88472_TS_MODE_PARALLEL
+
+/**
+ * struct mn88472_config - Platform data for the mn88472 driver
+ * @xtal: Clock frequency.
+ * @ts_mode: TS mode.
+ * @ts_clock: TS clock config.
+ * @i2c_wr_max: Max number of bytes driver writes to I2C at once.
+ * @fe: pointer to a frontend pointer
+ * @get_dvb_frontend: Get DVB frontend callback.
+ */
+struct mn88472_config {
+	unsigned int xtal;
+
+#define MN88472_TS_MODE_SERIAL      0
+#define MN88472_TS_MODE_PARALLEL    1
+	int ts_mode;
+
+#define MN88472_TS_CLK_FIXED        0
+#define MN88472_TS_CLK_VARIABLE     1
+	int ts_clock;
+
+	u16 i2c_wr_max;
+
+	/* Everything after that is returned by the driver. */
+
+	/*
+	 * DVB frontend.
+	 */
+	struct dvb_frontend **fe;
+	struct dvb_frontend* (*get_dvb_frontend)(struct i2c_client *);
+};
+
+#endif