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/isl6423.h b/drivers/media/dvb-frontends/isl6423.h
new file mode 100644
index 000000000..9fa87ceff
--- /dev/null
+++ b/drivers/media/dvb-frontends/isl6423.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+	Intersil ISL6423 SEC and LNB Power supply controller
+
+	Copyright (C) Manu Abraham <abraham.manu@gmail.com>
+
+*/
+
+#ifndef __ISL_6423_H
+#define __ISL_6423_H
+
+#include <linux/dvb/frontend.h>
+
+enum isl6423_current {
+	SEC_CURRENT_275m = 0,
+	SEC_CURRENT_515m,
+	SEC_CURRENT_635m,
+	SEC_CURRENT_800m,
+};
+
+enum isl6423_curlim {
+	SEC_CURRENT_LIM_ON = 1,
+	SEC_CURRENT_LIM_OFF
+};
+
+struct isl6423_config {
+	enum isl6423_current current_max;
+	enum isl6423_curlim curlim;
+	u8 addr;
+	u8 mod_extern;
+};
+
+#if IS_REACHABLE(CONFIG_DVB_ISL6423)
+
+
+extern struct dvb_frontend *isl6423_attach(struct dvb_frontend *fe,
+					   struct i2c_adapter *i2c,
+					   const struct isl6423_config *config);
+
+#else
+static inline struct dvb_frontend *isl6423_attach(struct dvb_frontend *fe,
+						  struct i2c_adapter *i2c,
+						  const struct isl6423_config *config)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+
+#endif /* CONFIG_DVB_ISL6423 */
+
+#endif /* __ISL_6423_H */