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, 76 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/dib8000.h b/drivers/media/dvb-frontends/dib8000.h
new file mode 100644
index 000000000..b920fe769
--- /dev/null
+++ b/drivers/media/dvb-frontends/dib8000.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef DIB8000_H
+#define DIB8000_H
+
+#include "dibx000_common.h"
+
+struct dib8000_config {
+	u8 output_mpeg2_in_188_bytes;
+	u8 hostbus_diversity;
+	u8 tuner_is_baseband;
+	int (*update_lna) (struct dvb_frontend *, u16 agc_global);
+
+	u8 agc_config_count;
+	struct dibx000_agc_config *agc;
+	struct dibx000_bandwidth_config *pll;
+
+#define DIB8000_GPIO_DEFAULT_DIRECTIONS 0xffff
+	u16 gpio_dir;
+#define DIB8000_GPIO_DEFAULT_VALUES     0x0000
+	u16 gpio_val;
+#define DIB8000_GPIO_PWM_POS0(v)        ((v & 0xf) << 12)
+#define DIB8000_GPIO_PWM_POS1(v)        ((v & 0xf) << 8 )
+#define DIB8000_GPIO_PWM_POS2(v)        ((v & 0xf) << 4 )
+#define DIB8000_GPIO_PWM_POS3(v)         (v & 0xf)
+#define DIB8000_GPIO_DEFAULT_PWM_POS    0xffff
+	u16 gpio_pwm_pos;
+	u16 pwm_freq_div;
+
+	void (*agc_control) (struct dvb_frontend *, u8 before);
+
+	u16 drives;
+	u16 diversity_delay;
+	u8 div_cfg;
+	u8 output_mode;
+	u8 refclksel;
+	u8 enMpegOutput:1;
+
+	struct dibx000_bandwidth_config *plltable;
+};
+
+#define DEFAULT_DIB8000_I2C_ADDRESS 18
+
+struct dib8000_ops {
+	int (*set_wbd_ref)(struct dvb_frontend *fe, u16 value);
+	int (*update_pll)(struct dvb_frontend *fe,
+		struct dibx000_bandwidth_config *pll, u32 bw, u8 ratio);
+	int (*set_gpio)(struct dvb_frontend *fe, u8 num, u8 dir, u8 val);
+	void (*pwm_agc_reset)(struct dvb_frontend *fe);
+	struct i2c_adapter *(*get_i2c_tuner)(struct dvb_frontend *fe);
+	int (*tuner_sleep)(struct dvb_frontend *fe, int onoff);
+	s32 (*get_adc_power)(struct dvb_frontend *fe, u8 mode);
+	int (*get_dc_power)(struct dvb_frontend *fe, u8 IQ);
+	u32 (*ctrl_timf)(struct dvb_frontend *fe, uint8_t op, uint32_t timf);
+	enum frontend_tune_state (*get_tune_state)(struct dvb_frontend *fe);
+	int (*set_tune_state)(struct dvb_frontend *fe, enum frontend_tune_state tune_state);
+	int (*set_slave_frontend)(struct dvb_frontend *fe, struct dvb_frontend *fe_slave);
+	struct dvb_frontend *(*get_slave_frontend)(struct dvb_frontend *fe, int slave_index);
+	int (*i2c_enumeration)(struct i2c_adapter *host, int no_of_demods,
+		u8 default_addr, u8 first_addr, u8 is_dib8096p);
+	struct i2c_adapter *(*get_i2c_master)(struct dvb_frontend *fe, enum dibx000_i2c_interface intf, int gating);
+	int (*pid_filter_ctrl)(struct dvb_frontend *fe, u8 onoff);
+	int (*pid_filter)(struct dvb_frontend *fe, u8 id, u16 pid, u8 onoff);
+	struct dvb_frontend *(*init)(struct i2c_adapter *i2c_adap, u8 i2c_addr, struct dib8000_config *cfg);
+};
+
+#if IS_REACHABLE(CONFIG_DVB_DIB8000)
+void *dib8000_attach(struct dib8000_ops *ops);
+#else
+static inline void *dib8000_attach(struct dib8000_ops *ops)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+#endif
+
+#endif