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, 140 insertions, 0 deletions

diff --git a/include/trace/events/sunvnet.h b/include/trace/events/sunvnet.h
new file mode 100644
index 000000000..8d444f1bb
--- /dev/null
+++ b/include/trace/events/sunvnet.h
@@ -0,0 +1,140 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM sunvnet
+
+#if !defined(_TRACE_SUNVNET_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SUNVNET_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(vnet_rx_one,
+
+	TP_PROTO(int lsid, int rsid, int index, int needs_ack),
+
+	TP_ARGS(lsid, rsid, index, needs_ack),
+
+	TP_STRUCT__entry(
+		__field(int, lsid)
+		__field(int, rsid)
+		__field(int, index)
+		__field(int, needs_ack)
+	),
+
+	TP_fast_assign(
+		__entry->lsid = lsid;
+		__entry->rsid = rsid;
+		__entry->index = index;
+		__entry->needs_ack = needs_ack;
+	),
+
+	TP_printk("(%x:%x) walk_rx_one index %d; needs_ack %d",
+		__entry->lsid, __entry->rsid,
+		__entry->index, __entry->needs_ack)
+);
+
+DECLARE_EVENT_CLASS(vnet_tx_stopped_ack_template,
+
+	TP_PROTO(int lsid, int rsid, int ack_end, int npkts),
+
+	TP_ARGS(lsid, rsid, ack_end, npkts),
+
+	TP_STRUCT__entry(
+		__field(int, lsid)
+		__field(int, rsid)
+		__field(int, ack_end)
+		__field(int, npkts)
+	),
+
+	TP_fast_assign(
+		__entry->lsid = lsid;
+		__entry->rsid = rsid;
+		__entry->ack_end = ack_end;
+		__entry->npkts = npkts;
+	),
+
+	TP_printk("(%x:%x) stopped ack for %d; npkts %d",
+		__entry->lsid, __entry->rsid,
+		__entry->ack_end, __entry->npkts)
+);
+DEFINE_EVENT(vnet_tx_stopped_ack_template, vnet_tx_send_stopped_ack,
+	     TP_PROTO(int lsid, int rsid, int ack_end, int npkts),
+	     TP_ARGS(lsid, rsid, ack_end, npkts));
+DEFINE_EVENT(vnet_tx_stopped_ack_template, vnet_tx_defer_stopped_ack,
+	     TP_PROTO(int lsid, int rsid, int ack_end, int npkts),
+	     TP_ARGS(lsid, rsid, ack_end, npkts));
+DEFINE_EVENT(vnet_tx_stopped_ack_template, vnet_tx_pending_stopped_ack,
+	     TP_PROTO(int lsid, int rsid, int ack_end, int npkts),
+	     TP_ARGS(lsid, rsid, ack_end, npkts));
+
+TRACE_EVENT(vnet_rx_stopped_ack,
+
+	TP_PROTO(int lsid, int rsid, int end),
+
+	TP_ARGS(lsid, rsid, end),
+
+	TP_STRUCT__entry(
+		__field(int, lsid)
+		__field(int, rsid)
+		__field(int, end)
+	),
+
+	TP_fast_assign(
+		__entry->lsid = lsid;
+		__entry->rsid = rsid;
+		__entry->end = end;
+	),
+
+	TP_printk("(%x:%x) stopped ack for index %d",
+		__entry->lsid, __entry->rsid, __entry->end)
+);
+
+TRACE_EVENT(vnet_tx_trigger,
+
+	TP_PROTO(int lsid, int rsid, int start, int err),
+
+	TP_ARGS(lsid, rsid, start, err),
+
+	TP_STRUCT__entry(
+		__field(int, lsid)
+		__field(int, rsid)
+		__field(int, start)
+		__field(int, err)
+	),
+
+	TP_fast_assign(
+		__entry->lsid = lsid;
+		__entry->rsid = rsid;
+		__entry->start = start;
+		__entry->err = err;
+	),
+
+	TP_printk("(%x:%x) Tx trigger for %d sent with err %d %s",
+		__entry->lsid, __entry->rsid, __entry->start,
+		__entry->err, __entry->err > 0 ? "(ok)" : " ")
+);
+
+TRACE_EVENT(vnet_skip_tx_trigger,
+
+	TP_PROTO(int lsid, int rsid, int last),
+
+	TP_ARGS(lsid, rsid, last),
+
+	TP_STRUCT__entry(
+		__field(int, lsid)
+		__field(int, rsid)
+		__field(int, last)
+	),
+
+	TP_fast_assign(
+		__entry->lsid = lsid;
+		__entry->rsid = rsid;
+		__entry->last = last;
+	),
+
+	TP_printk("(%x:%x) Skip Tx trigger. Last trigger sent was %d",
+		__entry->lsid, __entry->rsid, __entry->last)
+);
+#endif /* _TRACE_SOCK_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>