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, 48 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/stv6110.h b/drivers/media/dvb-frontends/stv6110.h
new file mode 100644
index 000000000..1cee9e62b
--- /dev/null
+++ b/drivers/media/dvb-frontends/stv6110.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * stv6110.h
+ *
+ * Driver for ST STV6110 satellite tuner IC.
+ *
+ * Copyright (C) 2009 NetUP Inc.
+ * Copyright (C) 2009 Igor M. Liplianin <liplianin@netup.ru>
+ */
+
+#ifndef __DVB_STV6110_H__
+#define __DVB_STV6110_H__
+
+#include <linux/i2c.h>
+#include <media/dvb_frontend.h>
+
+/* registers */
+#define RSTV6110_CTRL1		0
+#define RSTV6110_CTRL2		1
+#define RSTV6110_TUNING1	2
+#define RSTV6110_TUNING2	3
+#define RSTV6110_CTRL3		4
+#define RSTV6110_STAT1		5
+#define RSTV6110_STAT2		6
+#define RSTV6110_STAT3		7
+
+struct stv6110_config {
+	u8 i2c_address;
+	u32 mclk;
+	u8 gain;
+	u8 clk_div;	/* divisor value for the output clock */
+};
+
+#if IS_REACHABLE(CONFIG_DVB_STV6110)
+extern struct dvb_frontend *stv6110_attach(struct dvb_frontend *fe,
+					const struct stv6110_config *config,
+					struct i2c_adapter *i2c);
+#else
+static inline struct dvb_frontend *stv6110_attach(struct dvb_frontend *fe,
+					const struct stv6110_config *config,
+					struct i2c_adapter *i2c)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+#endif
+
+#endif