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, 88 insertions, 0 deletions

diff --git a/include/sound/i2c.h b/include/sound/i2c.h
new file mode 100644
index 000000000..6f0162ae9
--- /dev/null
+++ b/include/sound/i2c.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef __SOUND_I2C_H
+#define __SOUND_I2C_H
+
+/*
+ */
+
+#define SND_I2C_DEVICE_ADDRTEN	(1<<0)	/* 10-bit I2C address */
+
+struct snd_i2c_device {
+	struct list_head list;
+	struct snd_i2c_bus *bus;	/* I2C bus */
+	char name[32];		/* some useful device name */
+	unsigned short flags;	/* device flags */
+	unsigned short addr;	/* device address (might be 10-bit) */
+	unsigned long private_value;
+	void *private_data;
+	void (*private_free)(struct snd_i2c_device *device);
+};
+
+#define snd_i2c_device(n) list_entry(n, struct snd_i2c_device, list)
+
+struct snd_i2c_bit_ops {
+	void (*start)(struct snd_i2c_bus *bus);	/* transfer start */
+	void (*stop)(struct snd_i2c_bus *bus);	/* transfer stop */
+	void (*direction)(struct snd_i2c_bus *bus, int clock, int data);  /* set line direction (0 = write, 1 = read) */
+	void (*setlines)(struct snd_i2c_bus *bus, int clock, int data);
+	int (*getclock)(struct snd_i2c_bus *bus);
+	int (*getdata)(struct snd_i2c_bus *bus, int ack);
+};
+
+struct snd_i2c_ops {
+	int (*sendbytes)(struct snd_i2c_device *device, unsigned char *bytes, int count);
+	int (*readbytes)(struct snd_i2c_device *device, unsigned char *bytes, int count);
+	int (*probeaddr)(struct snd_i2c_bus *bus, unsigned short addr);
+};
+
+struct snd_i2c_bus {
+	struct snd_card *card;	/* card which I2C belongs to */
+	char name[32];		/* some useful label */
+
+	struct mutex lock_mutex;
+
+	struct snd_i2c_bus *master;	/* master bus when SCK/SCL is shared */
+	struct list_head buses;	/* master: slave buses sharing SCK/SCL, slave: link list */
+
+	struct list_head devices; /* attached devices to this bus */
+
+	union {
+		struct snd_i2c_bit_ops *bit;
+		void *ops;
+	} hw_ops;		/* lowlevel operations */
+	const struct snd_i2c_ops *ops;	/* midlevel operations */
+
+	unsigned long private_value;
+	void *private_data;
+	void (*private_free)(struct snd_i2c_bus *bus);
+};
+
+#define snd_i2c_slave_bus(n) list_entry(n, struct snd_i2c_bus, buses)
+
+int snd_i2c_bus_create(struct snd_card *card, const char *name,
+		       struct snd_i2c_bus *master, struct snd_i2c_bus **ri2c);
+int snd_i2c_device_create(struct snd_i2c_bus *bus, const char *name,
+			  unsigned char addr, struct snd_i2c_device **rdevice);
+int snd_i2c_device_free(struct snd_i2c_device *device);
+
+static inline void snd_i2c_lock(struct snd_i2c_bus *bus)
+{
+	if (bus->master)
+		mutex_lock(&bus->master->lock_mutex);
+	else
+		mutex_lock(&bus->lock_mutex);
+}
+
+static inline void snd_i2c_unlock(struct snd_i2c_bus *bus)
+{
+	if (bus->master)
+		mutex_unlock(&bus->master->lock_mutex);
+	else
+		mutex_unlock(&bus->lock_mutex);
+}
+
+int snd_i2c_sendbytes(struct snd_i2c_device *device, unsigned char *bytes, int count);
+int snd_i2c_readbytes(struct snd_i2c_device *device, unsigned char *bytes, int count);
+int snd_i2c_probeaddr(struct snd_i2c_bus *bus, unsigned short addr);
+
+#endif /* __SOUND_I2C_H */