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, 39 insertions, 0 deletions

diff --git a/tools/objtool/Build b/tools/objtool/Build
new file mode 100644
index 000000000..59f948628
--- /dev/null
+++ b/tools/objtool/Build
@@ -0,0 +1,39 @@
+objtool-y += arch/$(SRCARCH)/
+
+objtool-y += weak.o
+
+objtool-y += check.o
+objtool-y += special.o
+objtool-y += builtin-check.o
+objtool-y += elf.o
+objtool-y += klp-symid.o
+objtool-y += objtool.o
+
+objtool-$(BUILD_DISAS) += disas.o
+objtool-$(BUILD_DISAS) += trace.o
+
+objtool-$(BUILD_ORC) += orc_gen.o orc_dump.o
+objtool-$(BUILD_KLP) += builtin-klp.o klp-checksum.o klp-diff.o \
+			klp-post-link.o klp-sympos.o
+
+objtool-y += libstring.o
+objtool-y += libctype.o
+objtool-y += str_error_r.o
+objtool-y += librbtree.o
+objtool-y += signal.o
+
+$(OUTPUT)libstring.o: ../lib/string.c FORCE
+	$(call rule_mkdir)
+	$(call if_changed_dep,cc_o_c)
+
+$(OUTPUT)libctype.o: ../lib/ctype.c FORCE
+	$(call rule_mkdir)
+	$(call if_changed_dep,cc_o_c)
+
+$(OUTPUT)str_error_r.o: ../lib/str_error_r.c FORCE
+	$(call rule_mkdir)
+	$(call if_changed_dep,cc_o_c)
+
+$(OUTPUT)librbtree.o: ../lib/rbtree.c FORCE
+	$(call rule_mkdir)
+	$(call if_changed_dep,cc_o_c)