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, 32 insertions, 0 deletions

diff --git a/rust/helpers/device.c b/rust/helpers/device.c
new file mode 100644
index 000000000..3be4ee590
--- /dev/null
+++ b/rust/helpers/device.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/device.h>
+
+__rust_helper int rust_helper_devm_add_action(struct device *dev,
+					      void (*action)(void *),
+					      void *data)
+{
+	return devm_add_action(dev, action, data);
+}
+
+__rust_helper int rust_helper_devm_add_action_or_reset(struct device *dev,
+						       void (*action)(void *),
+						       void *data)
+{
+	return devm_add_action_or_reset(dev, action, data);
+}
+
+__rust_helper void *rust_helper_dev_get_drvdata(const struct device *dev)
+{
+	return dev_get_drvdata(dev);
+}
+
+__rust_helper void rust_helper_dev_set_drvdata(struct device *dev, void *data)
+{
+	dev_set_drvdata(dev, data);
+}
+
+__rust_helper const char *rust_helper_dev_name(const struct device *dev)
+{
+	return dev_name(dev);
+}