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, 55 insertions, 0 deletions

diff --git a/net/mac80211/trace_msg.h b/net/mac80211/trace_msg.h
new file mode 100644
index 000000000..aea4ce55c
--- /dev/null
+++ b/net/mac80211/trace_msg.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Portions of this file
+ * Copyright (C) 2019 Intel Corporation
+ */
+
+#ifdef CONFIG_MAC80211_MESSAGE_TRACING
+
+#if !defined(__MAC80211_MSG_DRIVER_TRACE) || defined(TRACE_HEADER_MULTI_READ)
+#define __MAC80211_MSG_DRIVER_TRACE
+
+#include <linux/tracepoint.h>
+#include <net/mac80211.h>
+#include "ieee80211_i.h"
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM mac80211_msg
+
+DECLARE_EVENT_CLASS(mac80211_msg_event,
+	TP_PROTO(struct va_format *vaf),
+
+	TP_ARGS(vaf),
+
+	TP_STRUCT__entry(
+		__vstring(msg, vaf->fmt, vaf->va)
+	),
+
+	TP_fast_assign(
+		__assign_vstr(msg, vaf->fmt, vaf->va);
+	),
+
+	TP_printk("%s", __get_str(msg))
+);
+
+DEFINE_EVENT(mac80211_msg_event, mac80211_info,
+	TP_PROTO(struct va_format *vaf),
+	TP_ARGS(vaf)
+);
+DEFINE_EVENT(mac80211_msg_event, mac80211_dbg,
+	TP_PROTO(struct va_format *vaf),
+	TP_ARGS(vaf)
+);
+DEFINE_EVENT(mac80211_msg_event, mac80211_err,
+	TP_PROTO(struct va_format *vaf),
+	TP_ARGS(vaf)
+);
+#endif /* !__MAC80211_MSG_DRIVER_TRACE || TRACE_HEADER_MULTI_READ */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE trace_msg
+#include <trace/define_trace.h>
+
+#endif