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, 33 insertions, 0 deletions

diff --git a/tools/testing/ktest/compare-ktest-sample.pl b/tools/testing/ktest/compare-ktest-sample.pl
new file mode 100755
index 000000000..ebea21d0a
--- /dev/null
+++ b/tools/testing/ktest/compare-ktest-sample.pl
@@ -0,0 +1,33 @@
+#!/usr/bin/env perl
+# SPDX-License-Identifier: GPL-2.0
+
+open (IN,"ktest.pl");
+while (<IN>) {
+    # hashes are now used
+    if (/\$opt\{"?([A-Z].*?)(\[.*\])?"?\}/ ||
+	/^\s*"?([A-Z].*?)"?\s*=>\s*/ ||
+	/set_test_option\("(.*?)"/) {
+	$opt{$1} = 1;
+    }
+}
+close IN;
+
+open (IN, "sample.conf");
+while (<IN>) {
+    if (/^\s*#?\s*([A-Z]\S*)\s*=/) {
+	$samp{$1} = 1;
+    }
+}
+close IN;
+
+foreach $opt (keys %opt) {
+    if (!defined($samp{$opt})) {
+	print "opt = $opt\n";
+    }
+}
+
+foreach $samp (keys %samp) {
+    if (!defined($opt{$samp})) {
+	print "samp = $samp\n";
+    }
+}