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, 107 insertions, 0 deletions

diff --git a/include/trace/events/iscsi.h b/include/trace/events/iscsi.h
new file mode 100644
index 000000000..990fd154f
--- /dev/null
+++ b/include/trace/events/iscsi.h
@@ -0,0 +1,107 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM iscsi
+
+#if !defined(_TRACE_ISCSI_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_ISCSI_H
+
+#include <linux/tracepoint.h>
+
+/* max debug message length */
+#define ISCSI_MSG_MAX	256
+
+/*
+ * Declare tracepoint helper function.
+ */
+void iscsi_dbg_trace(void (*trace)(struct device *dev, struct va_format *),
+		     struct device *dev, const char *fmt, ...);
+
+/*
+ * Declare event class for iscsi debug messages.
+ */
+DECLARE_EVENT_CLASS(iscsi_log_msg,
+
+	TP_PROTO(struct device *dev, struct va_format *vaf),
+
+	TP_ARGS(dev, vaf),
+
+	TP_STRUCT__entry(
+		__string(dname, 	dev_name(dev)		)
+		__vstring(msg,		vaf->fmt, vaf->va)
+	),
+
+	TP_fast_assign(
+		__assign_str(dname);
+		__assign_vstr(msg, vaf->fmt, vaf->va);
+	),
+
+	TP_printk("%s: %s",__get_str(dname),  __get_str(msg)
+	)
+);
+
+/*
+ * Define event to capture iscsi connection debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_conn,
+	TP_PROTO(struct device *dev, struct va_format *vaf),
+
+	TP_ARGS(dev, vaf)
+);
+
+/*
+ * Define event to capture iscsi session debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_session,
+	TP_PROTO(struct device *dev, struct va_format *vaf),
+
+	TP_ARGS(dev, vaf)
+);
+
+/*
+ * Define event to capture iscsi error handling debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_eh,
+        TP_PROTO(struct device *dev, struct va_format *vaf),
+
+        TP_ARGS(dev, vaf)
+);
+
+/*
+ * Define event to capture iscsi tcp debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_tcp,
+        TP_PROTO(struct device *dev, struct va_format *vaf),
+
+        TP_ARGS(dev, vaf)
+);
+
+/*
+ * Define event to capture iscsi sw tcp debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_sw_tcp,
+	TP_PROTO(struct device *dev, struct va_format *vaf),
+
+	TP_ARGS(dev, vaf)
+);
+
+/*
+ * Define event to capture iscsi transport session debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_trans_session,
+	TP_PROTO(struct device *dev, struct va_format *vaf),
+
+	TP_ARGS(dev, vaf)
+);
+
+/*
+ * Define event to capture iscsi transport connection debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_trans_conn,
+	TP_PROTO(struct device *dev, struct va_format *vaf),
+
+	TP_ARGS(dev, vaf)
+);
+
+#endif /* _TRACE_ISCSI_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>