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, 43 insertions, 0 deletions

diff --git a/scripts/Makefile.dtbinst b/scripts/Makefile.dtbinst
new file mode 100644
index 000000000..9d920419a
--- /dev/null
+++ b/scripts/Makefile.dtbinst
@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: GPL-2.0
+# ==========================================================================
+# Installing dtb files
+#
+# Installs all dtb files listed in $(dtb-y) either in the
+# INSTALL_DTBS_PATH directory or the default location:
+#
+#   $INSTALL_PATH/dtbs/$KERNELRELEASE
+# ==========================================================================
+
+PHONY := __dtbs_install
+__dtbs_install:
+
+include include/config/auto.conf
+include $(srctree)/scripts/Kbuild.include
+
+dst := $(INSTALL_DTBS_PATH)
+
+quiet_cmd_dtb_install = INSTALL $@
+      cmd_dtb_install = install -D -m 0644 $< $@
+
+$(dst)/%: $(obj)/%
+	$(call cmd,dtb_install)
+
+dtbs := $(patsubst $(obj)/%,%,$(call read-file, $(obj)/dtbs-list))
+
+ifdef CONFIG_ARCH_WANT_FLAT_DTB_INSTALL
+
+define gen_install_rules
+$(dst)/%: $(obj)/$(1)%
+	$$(call cmd,dtb_install)
+endef
+
+$(foreach d, $(sort $(dir $(dtbs))), $(eval $(call gen_install_rules,$(d))))
+
+dtbs := $(notdir $(dtbs))
+
+endif # CONFIG_ARCH_WANT_FLAT_DTB_INSTALL
+
+__dtbs_install: $(addprefix $(dst)/, $(dtbs))
+	@:
+
+.PHONY: $(PHONY)