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, 53 insertions, 0 deletions

diff --git a/scripts/kconfig/mnconf-common.c b/scripts/kconfig/mnconf-common.c
new file mode 100644
index 000000000..8e24b0712
--- /dev/null
+++ b/scripts/kconfig/mnconf-common.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <list.h>
+#include "expr.h"
+#include "mnconf-common.h"
+
+int jump_key_char;
+
+int next_jump_key(int key)
+{
+	if (key < '1' || key > '9')
+		return '1';
+
+	key++;
+
+	if (key > '9')
+		key = '1';
+
+	return key;
+}
+
+int handle_search_keys(int key, size_t start, size_t end, void *_data)
+{
+	struct search_data *data = _data;
+	struct jump_key *pos;
+	int index = 0;
+
+	if (key < '1' || key > '9')
+		return 0;
+
+	list_for_each_entry(pos, data->head, entries) {
+		index = next_jump_key(index);
+
+		if (pos->offset < start)
+			continue;
+
+		if (pos->offset >= end)
+			break;
+
+		if (key == index) {
+			data->target = pos->target;
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+int get_jump_key_char(void)
+{
+	jump_key_char = next_jump_key(jump_key_char);
+
+	return jump_key_char;
+}