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, 58 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/tdhd1.h b/drivers/media/dvb-frontends/tdhd1.h
new file mode 100644
index 000000000..55973a5fc
--- /dev/null
+++ b/drivers/media/dvb-frontends/tdhd1.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * tdhd1.h - ALPS TDHD1-204A tuner support
+ *
+ * Copyright (C) 2008 Oliver Endriss <o.endriss@gmx.de>
+ *
+ * The project's page is at https://linuxtv.org
+ */
+
+#ifndef TDHD1_H
+#define TDHD1_H
+
+#include "tda1004x.h"
+
+static int alps_tdhd1_204_request_firmware(struct dvb_frontend *fe, const struct firmware **fw, char *name);
+
+static struct tda1004x_config alps_tdhd1_204a_config = {
+	.demod_address = 0x8,
+	.invert = 1,
+	.invert_oclk = 0,
+	.xtal_freq = TDA10046_XTAL_4M,
+	.agc_config = TDA10046_AGC_DEFAULT,
+	.if_freq = TDA10046_FREQ_3617,
+	.request_firmware = alps_tdhd1_204_request_firmware
+};
+
+static int alps_tdhd1_204a_tuner_set_params(struct dvb_frontend *fe)
+{
+	struct dtv_frontend_properties *p = &fe->dtv_property_cache;
+	struct i2c_adapter *i2c = fe->tuner_priv;
+	u8 data[4];
+	struct i2c_msg msg = { .addr = 0x61, .flags = 0, .buf = data, .len = sizeof(data) };
+	u32 div;
+
+	div = (p->frequency + 36166666) / 166666;
+
+	data[0] = (div >> 8) & 0x7f;
+	data[1] = div & 0xff;
+	data[2] = 0x85;
+
+	if (p->frequency >= 174000000 && p->frequency <= 230000000)
+		data[3] = 0x02;
+	else if (p->frequency >= 470000000 && p->frequency <= 823000000)
+		data[3] = 0x0C;
+	else if (p->frequency > 823000000 && p->frequency <= 862000000)
+		data[3] = 0x8C;
+	else
+		return -EINVAL;
+
+	if (fe->ops.i2c_gate_ctrl)
+		fe->ops.i2c_gate_ctrl(fe, 1);
+	if (i2c_transfer(i2c, &msg, 1) != 1)
+		return -EIO;
+
+	return 0;
+}
+
+#endif /* TDHD1_H */