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, 14 insertions, 0 deletions

diff --git a/tools/perf/tests/pe-file.c b/tools/perf/tests/pe-file.c
new file mode 100644
index 000000000..eb3df5e98
--- /dev/null
+++ b/tools/perf/tests/pe-file.c
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0
+
+// pe-file.exe and pe-file.exe.debug built with;
+// x86_64-w64-mingw32-gcc -o pe-file.exe pe-file.c
+//   -Wl,--file-alignment,4096 -Wl,--build-id
+// x86_64-w64-mingw32-objcopy --only-keep-debug
+//   --compress-debug-sections pe-file.exe pe-file.exe.debug
+// x86_64-w64-mingw32-objcopy --strip-debug
+//   --add-gnu-debuglink=pe-file.exe.debug pe-file.exe
+
+int main(int argc, char const *argv[])
+{
+	return 0;
+}