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, 56 insertions, 0 deletions

diff --git a/drivers/base/trace.h b/drivers/base/trace.h
new file mode 100644
index 000000000..3b83b13a5
--- /dev/null
+++ b/drivers/base/trace.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Device core Trace Support
+ * Copyright (C) 2021, Intel Corporation
+ *
+ * Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM dev
+
+#if !defined(__DEV_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define __DEV_TRACE_H
+
+#include <linux/device.h>
+#include <linux/tracepoint.h>
+#include <linux/types.h>
+
+DECLARE_EVENT_CLASS(devres,
+	TP_PROTO(struct device *dev, const char *op, void *node, const char *name, size_t size),
+	TP_ARGS(dev, op, node, name, size),
+	TP_STRUCT__entry(
+		__string(devname, dev_name(dev))
+		__field(struct device *, dev)
+		__field(const char *, op)
+		__field(void *, node)
+		__string(name, name)
+		__field(size_t, size)
+	),
+	TP_fast_assign(
+		__assign_str(devname);
+		__entry->op = op;
+		__entry->node = node;
+		__assign_str(name);
+		__entry->size = size;
+	),
+	TP_printk("%s %3s %p %s (%zu bytes)", __get_str(devname),
+		  __entry->op, __entry->node, __get_str(name), __entry->size)
+);
+
+DEFINE_EVENT(devres, devres_log,
+	TP_PROTO(struct device *dev, const char *op, void *node, const char *name, size_t size),
+	TP_ARGS(dev, op, node, name, size)
+);
+
+#endif /* __DEV_TRACE_H */
+
+/* this part has to be here */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE trace
+
+#include <trace/define_trace.h>