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, 73 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/dib0070.h b/drivers/media/dvb-frontends/dib0070.h
new file mode 100644
index 000000000..ae5c44e9b
--- /dev/null
+++ b/drivers/media/dvb-frontends/dib0070.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Linux-DVB Driver for DiBcom's DiB0070 base-band RF Tuner.
+ *
+ * Copyright (C) 2005-7 DiBcom (http://www.dibcom.fr/)
+ */
+#ifndef DIB0070_H
+#define DIB0070_H
+
+struct dvb_frontend;
+struct i2c_adapter;
+
+#define DEFAULT_DIB0070_I2C_ADDRESS 0x60
+
+struct dib0070_wbd_gain_cfg {
+	u16 freq;
+	u16 wbd_gain_val;
+};
+
+struct dib0070_config {
+	u8 i2c_address;
+
+	/* tuner pins controlled externally */
+	int (*reset) (struct dvb_frontend *, int);
+	int (*sleep) (struct dvb_frontend *, int);
+
+	/*  offset in kHz */
+	int freq_offset_khz_uhf;
+	int freq_offset_khz_vhf;
+
+	u8 osc_buffer_state;	/* 0= normal, 1= tri-state */
+	u32 clock_khz;
+	u8 clock_pad_drive;	/* (Drive + 1) * 2mA */
+
+	u8 invert_iq;		/* invert Q - in case I or Q is inverted on the board */
+
+	u8 force_crystal_mode;	/* if == 0 -> decision is made in the driver default: <24 -> 2, >=24 -> 1 */
+
+	u8 flip_chip;
+	u8 enable_third_order_filter;
+	u8 charge_pump;
+
+	const struct dib0070_wbd_gain_cfg *wbd_gain;
+
+	u8 vga_filter;
+};
+
+#if IS_REACHABLE(CONFIG_DVB_TUNER_DIB0070)
+extern struct dvb_frontend *dib0070_attach(struct dvb_frontend *fe, struct i2c_adapter *i2c, struct dib0070_config *cfg);
+extern u16 dib0070_wbd_offset(struct dvb_frontend *);
+extern void dib0070_ctrl_agc_filter(struct dvb_frontend *, u8 open);
+extern u8 dib0070_get_rf_output(struct dvb_frontend *fe);
+extern int dib0070_set_rf_output(struct dvb_frontend *fe, u8 no);
+#else
+static inline struct dvb_frontend *dib0070_attach(struct dvb_frontend *fe, struct i2c_adapter *i2c, struct dib0070_config *cfg)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+
+static inline u16 dib0070_wbd_offset(struct dvb_frontend *fe)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return 0;
+}
+
+static inline void dib0070_ctrl_agc_filter(struct dvb_frontend *fe, u8 open)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+}
+#endif
+
+#endif