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, 62 insertions, 0 deletions

diff --git a/sound/firewire/fireface/ff-proc.c b/sound/firewire/fireface/ff-proc.c
new file mode 100644
index 000000000..4aecc8dcb
--- /dev/null
+++ b/sound/firewire/fireface/ff-proc.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ff-proc.c - a part of driver for RME Fireface series
+ *
+ * Copyright (c) 2015-2017 Takashi Sakamoto
+ */
+
+#include "./ff.h"
+
+const char *snd_ff_proc_get_clk_label(enum snd_ff_clock_src src)
+{
+	static const char *const labels[] = {
+		"Internal",
+		"S/PDIF",
+		"ADAT1",
+		"ADAT2",
+		"Word",
+		"LTC",
+	};
+
+	if (src >= ARRAY_SIZE(labels))
+		return NULL;
+
+	return labels[src];
+}
+
+static void proc_dump_status(struct snd_info_entry *entry,
+			     struct snd_info_buffer *buffer)
+{
+	struct snd_ff *ff = entry->private_data;
+
+	ff->spec->protocol->dump_status(ff, buffer);
+}
+
+static void add_node(struct snd_ff *ff, struct snd_info_entry *root,
+		     const char *name,
+		     void (*op)(struct snd_info_entry *e,
+				struct snd_info_buffer *b))
+{
+	struct snd_info_entry *entry;
+
+	entry = snd_info_create_card_entry(ff->card, name, root);
+	if (entry)
+		snd_info_set_text_ops(entry, ff, op);
+}
+
+void snd_ff_proc_init(struct snd_ff *ff)
+{
+	struct snd_info_entry *root;
+
+	/*
+	 * All nodes are automatically removed at snd_card_disconnect(),
+	 * by following to link list.
+	 */
+	root = snd_info_create_card_entry(ff->card, "firewire",
+					  ff->card->proc_root);
+	if (root == NULL)
+		return;
+	root->mode = S_IFDIR | 0555;
+
+	add_node(ff, root, "status", proc_dump_status);
+}