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, 45 insertions, 0 deletions

diff --git a/sound/soc/codecs/src4xxx-i2c.c b/sound/soc/codecs/src4xxx-i2c.c
new file mode 100644
index 000000000..4157f7787
--- /dev/null
+++ b/sound/soc/codecs/src4xxx-i2c.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Driver for SRC4XXX codecs
+//
+// Copyright 2021-2022 Deqx Pty Ltd
+// Author: Matt Flax <flatmax@flatmax.com>
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include "src4xxx.h"
+
+static int src4xxx_i2c_probe(struct i2c_client *i2c)
+{
+	return src4xxx_probe(&i2c->dev,
+		devm_regmap_init_i2c(i2c, &src4xxx_regmap_config), NULL);
+}
+
+static const struct i2c_device_id src4xxx_i2c_ids[] = {
+	{ .name = "src4392" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, src4xxx_i2c_ids);
+
+static const struct of_device_id src4xxx_of_match[] __maybe_unused = {
+	{ .compatible = "ti,src4392", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, src4xxx_of_match);
+
+
+static struct i2c_driver src4xxx_i2c_driver = {
+	.driver = {
+		.name = "src4xxx",
+		.of_match_table = of_match_ptr(src4xxx_of_match),
+	},
+	.probe = src4xxx_i2c_probe,
+	.id_table = src4xxx_i2c_ids,
+};
+module_i2c_driver(src4xxx_i2c_driver);
+
+MODULE_DESCRIPTION("ASoC SRC4392 CODEC I2C driver");
+MODULE_AUTHOR("Matt Flax <flatmax@flatmax.com>");
+MODULE_LICENSE("GPL");