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, 31 insertions, 0 deletions

diff --git a/arch/arm/mach-omap2/common.c b/arch/arm/mach-omap2/common.c
new file mode 100644
index 000000000..a4af202cb
--- /dev/null
+++ b/arch/arm/mach-omap2/common.c
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/arch/arm/mach-omap2/common.c
+ *
+ * Code common to all OMAP2+ machines.
+ *
+ * Copyright (C) 2009 Texas Instruments
+ * Copyright (C) 2010 Nokia Corporation
+ * Tony Lindgren <tony@atomide.com>
+ * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+
+#include "common.h"
+#include "omap-secure.h"
+
+/*
+ * Stub function for OMAP2 so that common files
+ * continue to build when custom builds are used
+ */
+int __weak omap_secure_ram_reserve_memblock(void)
+{
+	return 0;
+}
+
+void __init omap_reserve(void)
+{
+	omap_secure_ram_reserve_memblock();
+	omap_barrier_reserve_memblock();
+}