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, 26 insertions, 0 deletions

diff --git a/scripts/Lindent b/scripts/Lindent
new file mode 100755
index 000000000..1688c44c2
--- /dev/null
+++ b/scripts/Lindent
@@ -0,0 +1,26 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+PARAM="-npro -kr -i8 -ts8 -sob -l80 -ss -ncs -cp1"
+
+RES=`indent --version | cut -d' ' -f3`
+if [ "$RES" = "" ]; then
+	exit 1
+fi
+V1=`echo $RES | cut -d'.' -f1`
+V2=`echo $RES | cut -d'.' -f2`
+V3=`echo $RES | cut -d'.' -f3`
+
+if [ $V1 -gt 2 ]; then
+  PARAM="$PARAM -il0"
+elif [ $V1 -eq 2 ]; then
+  if [ $V2 -gt 2 ]; then
+    PARAM="$PARAM -il0"
+  elif [ $V2 -eq 2 ]; then
+    if [ $V3 -ge 10 ]; then
+      PARAM="$PARAM -il0"
+    fi
+  fi
+fi
+
+indent $PARAM "$@"