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, 46 insertions, 0 deletions

diff --git a/drivers/tty/ipwireless/tty.h b/drivers/tty/ipwireless/tty.h
new file mode 100644
index 000000000..ec698d9f3
--- /dev/null
+++ b/drivers/tty/ipwireless/tty.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * IPWireless 3G PCMCIA Network Driver
+ *
+ * Original code
+ *   by Stephen Blackheath <stephen@blacksapphire.com>,
+ *      Ben Martel <benm@symmetric.co.nz>
+ *
+ * Copyrighted as follows:
+ *   Copyright (C) 2004 by Symmetric Systems Ltd (NZ)
+ *
+ * Various driver changes and rewrites, port to new kernels
+ *   Copyright (C) 2006-2007 Jiri Kosina
+ *
+ * Misc code cleanups and updates
+ *   Copyright (C) 2007 David Sterba
+ */
+
+#ifndef _IPWIRELESS_CS_TTY_H_
+#define _IPWIRELESS_CS_TTY_H_
+
+#include <linux/types.h>
+#include <linux/sched.h>
+
+#include <pcmcia/cistpl.h>
+#include <pcmcia/ds.h>
+
+struct ipw_tty;
+struct ipw_network;
+struct ipw_hardware;
+
+int ipwireless_tty_init(void);
+void ipwireless_tty_release(void);
+
+struct ipw_tty *ipwireless_tty_create(struct ipw_hardware *hw,
+				      struct ipw_network *net);
+void ipwireless_tty_free(struct ipw_tty *tty);
+void ipwireless_tty_received(struct ipw_tty *tty, unsigned char *data,
+			     unsigned int length);
+int ipwireless_tty_is_modem(struct ipw_tty *tty);
+void ipwireless_tty_notify_control_line_change(struct ipw_tty *tty,
+					       unsigned int channel_idx,
+					       unsigned int control_lines,
+					       unsigned int changed_mask);
+
+#endif