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/st95hf/spi.h b/drivers/nfc/st95hf/spi.h
new file mode 100644
index 000000000..3ab678734
--- /dev/null
+++ b/drivers/nfc/st95hf/spi.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * ---------------------------------------------------------------------------
+ * drivers/nfc/st95hf/spi.h functions declarations for SPI communication
+ * ---------------------------------------------------------------------------
+ * Copyright (C) 2015 STMicroelectronics – All Rights Reserved
+ */
+
+#ifndef __LINUX_ST95HF_SPI_H
+#define __LINUX_ST95HF_SPI_H
+
+#include <linux/spi/spi.h>
+
+/* Basic ST95HF SPI CMDs */
+#define ST95HF_COMMAND_SEND	0x0
+#define ST95HF_COMMAND_RESET	0x1
+#define ST95HF_COMMAND_RECEIVE	0x2
+
+#define ST95HF_RESET_CMD_LEN	0x1
+
+/*
+ * structure to contain st95hf spi communication specific information.
+ * @req_issync: true for synchronous calls.
+ * @spidev: st95hf spi device object.
+ * @done: completion structure to wait for st95hf response
+ *	for synchronous calls.
+ * @spi_lock: mutex to allow only one spi transfer at a time.
+ */
+struct st95hf_spi_context {
+	bool req_issync;
+	struct spi_device *spidev;
+	struct completion done;
+	struct mutex spi_lock;
+};
+
+/* flag to differentiate synchronous & asynchronous spi request */
+enum req_type {
+	SYNC,
+	ASYNC,
+};
+
+int st95hf_spi_send(struct st95hf_spi_context *spicontext,
+		    unsigned char *buffertx,
+		    int datalen,
+		    enum req_type reqtype);
+
+int st95hf_spi_recv_response(struct st95hf_spi_context *spicontext,
+			     unsigned char *receivebuff);
+
+int st95hf_spi_recv_echo_res(struct st95hf_spi_context *spicontext,
+			     unsigned char *receivebuff);
+
+#endif