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, 53 insertions, 0 deletions

diff --git a/drivers/nfc/mei_phy.h b/drivers/nfc/mei_phy.h
new file mode 100644
index 000000000..9b9c5eb54
--- /dev/null
+++ b/drivers/nfc/mei_phy.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LOCAL_MEI_PHY_H_
+#define __LOCAL_MEI_PHY_H_
+
+#include <linux/mei_cl_bus.h>
+#include <net/nfc/hci.h>
+#include <linux/uuid.h>
+
+#define MEI_NFC_UUID UUID_LE(0x0bb17a78, 0x2a8e, 0x4c50, \
+		0x94, 0xd4, 0x50, 0x26, 0x67, 0x23, 0x77, 0x5c)
+#define MEI_NFC_HEADER_SIZE 10
+#define MEI_NFC_MAX_HCI_PAYLOAD 300
+
+/**
+ * struct nfc_mei_phy - NFC description of the MEI PHY and interface functions
+ *
+ * @cldev: mei client device
+ * @hdev:   nfc hci device
+ *
+ * @send_wq: send completion wait queue
+ * @fw_ivn: NFC Interface Version Number
+ * @vendor_id: NFC manufacturer ID
+ * @radio_type: NFC radio type
+ * @reserved: reserved for alignment
+ * @req_id:  message counter
+ * @recv_req_id: reception message counter
+ * @powered: the device is in powered state
+ * @hard_fault: < 0 if hardware error occurred
+ *    and prevents normal operation.
+ */
+struct nfc_mei_phy {
+	struct mei_cl_device *cldev;
+	struct nfc_hci_dev *hdev;
+
+	wait_queue_head_t send_wq;
+	u8 fw_ivn;
+	u8 vendor_id;
+	u8 radio_type;
+	u8 reserved;
+
+	u16 req_id;
+	u16 recv_req_id;
+
+	int powered;
+	int hard_fault;
+};
+
+extern const struct nfc_phy_ops mei_phy_ops;
+
+struct nfc_mei_phy *nfc_mei_phy_alloc(struct mei_cl_device *device);
+void nfc_mei_phy_free(struct nfc_mei_phy *phy);
+
+#endif /* __LOCAL_MEI_PHY_H_ */