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, 78 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/dib7000p.h b/drivers/media/dvb-frontends/dib7000p.h
new file mode 100644
index 000000000..2e10b5ccc
--- /dev/null
+++ b/drivers/media/dvb-frontends/dib7000p.h
@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef DIB7000P_H
+#define DIB7000P_H
+
+#include "dibx000_common.h"
+
+struct dib7000p_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 *bw;
+
+#define DIB7000P_GPIO_DEFAULT_DIRECTIONS 0xffff
+	u16 gpio_dir;
+#define DIB7000P_GPIO_DEFAULT_VALUES     0x0000
+	u16 gpio_val;
+#define DIB7000P_GPIO_PWM_POS0(v)        ((v & 0xf) << 12)
+#define DIB7000P_GPIO_PWM_POS1(v)        ((v & 0xf) << 8 )
+#define DIB7000P_GPIO_PWM_POS2(v)        ((v & 0xf) << 4 )
+#define DIB7000P_GPIO_PWM_POS3(v)         (v & 0xf)
+#define DIB7000P_GPIO_DEFAULT_PWM_POS    0xffff
+	u16 gpio_pwm_pos;
+
+	u16 pwm_freq_div;
+
+	u8 quartz_direct;
+
+	u8 spur_protect;
+
+	int (*agc_control) (struct dvb_frontend *, u8 before);
+
+	u8 output_mode;
+	u8 disable_sample_and_hold:1;
+
+	u8 enable_current_mirror:1;
+	u16 diversity_delay;
+
+	u8 default_i2c_addr;
+	u8 enMpegOutput:1;
+};
+
+#define DEFAULT_DIB7000P_I2C_ADDRESS 18
+
+struct dib7000p_ops {
+	int (*set_wbd_ref)(struct dvb_frontend *demod, u16 value);
+	int (*get_agc_values)(struct dvb_frontend *fe,
+		u16 *agc_global, u16 *agc1, u16 *agc2, u16 *wbd);
+	int (*set_agc1_min)(struct dvb_frontend *fe, u16 v);
+	int (*update_pll)(struct dvb_frontend *fe, struct dibx000_bandwidth_config *bw);
+	int (*set_gpio)(struct dvb_frontend *demod, u8 num, u8 dir, u8 val);
+	u32 (*ctrl_timf)(struct dvb_frontend *fe, u8 op, u32 timf);
+	int (*dib7000pc_detection)(struct i2c_adapter *i2c_adap);
+	struct i2c_adapter *(*get_i2c_master)(struct dvb_frontend *demod, 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);
+	int (*i2c_enumeration)(struct i2c_adapter *i2c, int no_of_demods, u8 default_addr, struct dib7000p_config cfg[]);
+	struct i2c_adapter *(*get_i2c_tuner)(struct dvb_frontend *fe);
+	int (*tuner_sleep)(struct dvb_frontend *fe, int onoff);
+	int (*get_adc_power)(struct dvb_frontend *fe);
+	int (*slave_reset)(struct dvb_frontend *fe);
+	struct dvb_frontend *(*init)(struct i2c_adapter *i2c_adap, u8 i2c_addr, struct dib7000p_config *cfg);
+};
+
+#if IS_REACHABLE(CONFIG_DVB_DIB7000P)
+void *dib7000p_attach(struct dib7000p_ops *ops);
+#else
+static inline void *dib7000p_attach(struct dib7000p_ops *ops)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+#endif
+
+#endif