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, 19 insertions, 0 deletions

diff --git a/Documentation/sphinx/templates/kernel-toc.html b/Documentation/sphinx/templates/kernel-toc.html
new file mode 100644
index 000000000..b84969bd3
--- /dev/null
+++ b/Documentation/sphinx/templates/kernel-toc.html
@@ -0,0 +1,19 @@
+{# SPDX-License-Identifier: GPL-2.0 #}
+
+{# Create a local TOC the kernel way #}
+<p>
+<h3 class="kernel-toc-contents">Contents</h3>
+<input type="checkbox" class="kernel-toc-toggle" id = "kernel-toc-toggle" checked>
+<label class="kernel-toc-title" for="kernel-toc-toggle"></label>
+
+<div class="kerneltoc" id="kerneltoc">
+{{ toctree(maxdepth=3) }}
+</div>
+{# hacky script to try to position the left column #}
+<script type="text/javascript"> <!--
+  var sbar = document.getElementsByClassName("sphinxsidebar")[0];
+  let currents = document.getElementsByClassName("current")
+  if (currents.length) {
+    sbar.scrollTop = currents[currents.length - 1].offsetTop;
+  }
+  --> </script>