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, 57 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/ascot2e.h b/drivers/media/dvb-frontends/ascot2e.h
new file mode 100644
index 000000000..d86b3de85
--- /dev/null
+++ b/drivers/media/dvb-frontends/ascot2e.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * ascot2e.h
+ *
+ * Sony Ascot3E DVB-T/T2/C/C2 tuner driver
+ *
+ * Copyright 2012 Sony Corporation
+ * Copyright (C) 2014 NetUP Inc.
+ * Copyright (C) 2014 Sergey Kozlov <serjk@netup.ru>
+ * Copyright (C) 2014 Abylay Ospan <aospan@netup.ru>
+  */
+
+#ifndef __DVB_ASCOT2E_H__
+#define __DVB_ASCOT2E_H__
+
+#include <linux/dvb/frontend.h>
+#include <linux/i2c.h>
+
+/**
+ * struct ascot2e_config - the configuration of Ascot2E tuner driver
+ * @i2c_address:	I2C address of the tuner
+ * @xtal_freq_mhz:	Oscillator frequency, MHz
+ * @set_tuner_priv:	Callback function private context
+ * @set_tuner_callback:	Callback function that notifies the parent driver
+ *			which tuner is active now
+ */
+struct ascot2e_config {
+	u8	i2c_address;
+	u8	xtal_freq_mhz;
+	void	*set_tuner_priv;
+	int	(*set_tuner_callback)(void *, int);
+};
+
+#if IS_REACHABLE(CONFIG_DVB_ASCOT2E)
+/**
+ * ascot2e_attach - Attach an ascot2e tuner
+ *
+ * @fe: frontend to be attached
+ * @config: pointer to &struct ascot2e_config with tuner configuration.
+ * @i2c: i2c adapter to use.
+ *
+ * return: FE pointer on success, NULL on failure.
+ */
+extern struct dvb_frontend *ascot2e_attach(struct dvb_frontend *fe,
+					const struct ascot2e_config *config,
+					struct i2c_adapter *i2c);
+#else
+static inline struct dvb_frontend *ascot2e_attach(struct dvb_frontend *fe,
+					const struct ascot2e_config *config,
+					struct i2c_adapter *i2c)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+#endif
+
+#endif