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, 59 insertions, 0 deletions

diff --git a/sound/soc/codecs/sigmadsp-regmap.c b/sound/soc/codecs/sigmadsp-regmap.c
new file mode 100644
index 000000000..ba9a6795e
--- /dev/null
+++ b/sound/soc/codecs/sigmadsp-regmap.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Load Analog Devices SigmaStudio firmware files
+ *
+ * Copyright 2009-2011 Analog Devices Inc.
+ */
+
+#include <linux/regmap.h>
+#include <linux/export.h>
+#include <linux/module.h>
+
+#include "sigmadsp.h"
+
+static int sigmadsp_write_regmap(void *control_data,
+	unsigned int addr, const uint8_t data[], size_t len)
+{
+	return regmap_raw_write(control_data, addr,
+		data, len);
+}
+
+static int sigmadsp_read_regmap(void *control_data,
+	unsigned int addr, uint8_t data[], size_t len)
+{
+	return regmap_raw_read(control_data, addr,
+		data, len);
+}
+
+/**
+ * devm_sigmadsp_init_regmap() - Initialize SigmaDSP instance
+ * @dev: The parent device
+ * @regmap: Regmap instance to use
+ * @ops: The sigmadsp_ops to use for this instance
+ * @firmware_name: Name of the firmware file to load
+ *
+ * Allocates a SigmaDSP instance and loads the specified firmware file.
+ *
+ * Returns a pointer to a struct sigmadsp on success, or a PTR_ERR() on error.
+ */
+struct sigmadsp *devm_sigmadsp_init_regmap(struct device *dev,
+	struct regmap *regmap, const struct sigmadsp_ops *ops,
+	const char *firmware_name)
+{
+	struct sigmadsp *sigmadsp;
+
+	sigmadsp = devm_sigmadsp_init(dev, ops, firmware_name);
+	if (IS_ERR(sigmadsp))
+		return sigmadsp;
+
+	sigmadsp->control_data = regmap;
+	sigmadsp->write = sigmadsp_write_regmap;
+	sigmadsp->read = sigmadsp_read_regmap;
+
+	return sigmadsp;
+}
+EXPORT_SYMBOL_GPL(devm_sigmadsp_init_regmap);
+
+MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
+MODULE_DESCRIPTION("SigmaDSP regmap firmware loader");
+MODULE_LICENSE("GPL");