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, 79 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/au8522.h b/drivers/media/dvb-frontends/au8522.h
new file mode 100644
index 000000000..72e332857
--- /dev/null
+++ b/drivers/media/dvb-frontends/au8522.h
@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+    Auvitek AU8522 QAM/8VSB demodulator driver
+
+    Copyright (C) 2008 Steven Toth <stoth@linuxtv.org>
+
+
+*/
+
+#ifndef __AU8522_H__
+#define __AU8522_H__
+
+#include <linux/dvb/frontend.h>
+
+enum au8522_if_freq {
+	AU8522_IF_6MHZ = 0,
+	AU8522_IF_4MHZ,
+	AU8522_IF_3_25MHZ,
+};
+
+struct au8522_led_config {
+	u16 vsb8_strong;
+	u16 qam64_strong;
+	u16 qam256_strong;
+
+	u16 gpio_output;
+	/* unset hi bits, set low bits */
+	u16 gpio_output_enable;
+	u16 gpio_output_disable;
+
+	u16 gpio_leds;
+	u8 *led_states;
+	unsigned int num_led_states;
+};
+
+struct au8522_config {
+	/* the demodulator's i2c address */
+	u8 demod_address;
+
+	/* Return lock status based on tuner lock, or demod lock */
+#define AU8522_TUNERLOCKING 0
+#define AU8522_DEMODLOCKING 1
+	u8 status_mode;
+
+	struct au8522_led_config *led_cfg;
+
+	enum au8522_if_freq vsb_if;
+	enum au8522_if_freq qam_if;
+};
+
+#if IS_REACHABLE(CONFIG_DVB_AU8522_DTV)
+extern struct dvb_frontend *au8522_attach(const struct au8522_config *config,
+					  struct i2c_adapter *i2c);
+#else
+static inline
+struct dvb_frontend *au8522_attach(const struct au8522_config *config,
+				   struct i2c_adapter *i2c)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+#endif /* CONFIG_DVB_AU8522 */
+
+/* Other modes may need to be added later */
+enum au8522_video_input {
+	AU8522_COMPOSITE_CH1 = 1,
+	AU8522_COMPOSITE_CH2,
+	AU8522_COMPOSITE_CH3,
+	AU8522_COMPOSITE_CH4,
+	AU8522_COMPOSITE_CH4_SIF,
+	AU8522_SVIDEO_CH13,
+	AU8522_SVIDEO_CH24,
+};
+
+enum au8522_audio_input {
+	AU8522_AUDIO_NONE,
+	AU8522_AUDIO_SIF,
+};
+#endif /* __AU8522_H__ */