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, 67 insertions, 0 deletions

diff --git a/include/asm-generic/irqflags.h b/include/asm-generic/irqflags.h
new file mode 100644
index 000000000..19ccbf483
--- /dev/null
+++ b/include/asm-generic/irqflags.h
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_GENERIC_IRQFLAGS_H
+#define __ASM_GENERIC_IRQFLAGS_H
+
+/*
+ * All architectures should implement at least the first two functions,
+ * usually inline assembly will be the best way.
+ */
+#ifndef ARCH_IRQ_DISABLED
+#define ARCH_IRQ_DISABLED 0
+#define ARCH_IRQ_ENABLED 1
+#endif
+
+/* read interrupt enabled status */
+#ifndef arch_local_save_flags
+unsigned long arch_local_save_flags(void);
+#endif
+
+/* set interrupt enabled status */
+#ifndef arch_local_irq_restore
+void arch_local_irq_restore(unsigned long flags);
+#endif
+
+/* get status and disable interrupts */
+#ifndef arch_local_irq_save
+static inline unsigned long arch_local_irq_save(void)
+{
+	unsigned long flags;
+	flags = arch_local_save_flags();
+	arch_local_irq_restore(ARCH_IRQ_DISABLED);
+	return flags;
+}
+#endif
+
+/* test flags */
+#ifndef arch_irqs_disabled_flags
+static inline int arch_irqs_disabled_flags(unsigned long flags)
+{
+	return flags == ARCH_IRQ_DISABLED;
+}
+#endif
+
+/* unconditionally enable interrupts */
+#ifndef arch_local_irq_enable
+static inline void arch_local_irq_enable(void)
+{
+	arch_local_irq_restore(ARCH_IRQ_ENABLED);
+}
+#endif
+
+/* unconditionally disable interrupts */
+#ifndef arch_local_irq_disable
+static inline void arch_local_irq_disable(void)
+{
+	arch_local_irq_restore(ARCH_IRQ_DISABLED);
+}
+#endif
+
+/* test hardware interrupt enable bit */
+#ifndef arch_irqs_disabled
+static inline int arch_irqs_disabled(void)
+{
+	return arch_irqs_disabled_flags(arch_local_save_flags());
+}
+#endif
+
+#endif /* __ASM_GENERIC_IRQFLAGS_H */